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xAVIC and x2AVIC modes can support diffferent number of vcpus.
Update existing logics to support each mode accordingly.
Also, modify the maximum physical APIC ID for AVIC to 255 to reflect
the actual value supported by the architecture.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Message-Id: <20220519102709.24125-5-suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Add CPUID check for the x2APIC virtualization (x2AVIC) feature.
If available, the SVM driver can support both AVIC and x2AVIC modes
when load the kvm_amd driver with avic=1. The operating mode will be
determined at runtime depending on the guest APIC mode.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Message-Id: <20220519102709.24125-4-suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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To signify that the macros only support 8-bit xAPIC destination ID.
Suggested-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220519102709.24125-3-suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Introduce a new feature bit for virtualized x2APIC (x2AVIC) in
CPUID_Fn8000000A_EDX [SVM Revision and Feature Identification].
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220519102709.24125-2-suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Rely on try_cmpxchg64 for re-reading the PID on failure, using READ_ONCE
only right before the first iteration.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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This patch enables MCG_CMCI_P by default in kvm_mce_cap_supported. It
reuses ioctl KVM_X86_SET_MCE to implement injection of UnCorrectable
No Action required (UCNA) errors, signaled via Corrected Machine
Check Interrupt (CMCI).
Neither of the CMCI and UCNA emulations depends on hardware.
Signed-off-by: Jue Wang <juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220610171134.772566-8-juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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This patch adds the emulation of IA32_MCi_CTL2 registers to KVM. A
separate mci_ctl2_banks array is used to keep the existing mce_banks
register layout intact.
In Machine Check Architecture, in addition to MCG_CMCI_P, bit 30 of
the per-bank register IA32_MCi_CTL2 controls whether Corrected Machine
Check error reporting is enabled.
Signed-off-by: Jue Wang <juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220610171134.772566-7-juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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This patch updates the allocation of mce_banks with the array allocation
API (kcalloc) as a precedent for the later mci_ctl2_banks to implement
per-bank control of Corrected Machine Check Interrupt (CMCI).
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Jue Wang <juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220610171134.772566-6-juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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This patch calculates the number of lvt entries as part of
KVM_X86_MCE_SETUP conditioned on the presence of MCG_CMCI_P bit in
MCG_CAP and stores result in kvm_lapic. It translats from APIC_LVTx
register to index in lapic_lvt_entry enum. It extends the APIC_LVTx
macro as well as other lapic write/reset handling etc to support
Corrected Machine Check Interrupt.
Signed-off-by: Jue Wang <juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220610171134.772566-5-juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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An APIC_LVTx macro is introduced to calcualte the APIC_LVTx register
offset based on the index in the lapic_lvt_entry enum. Later patches
will extend the APIC_LVTx macro to support the APIC_LVTCMCI register
in order to implement Corrected Machine Check Interrupt signaling.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Jue Wang <juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220610171134.772566-4-juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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This patch defines a lapic_lvt_entry enum used as explicit indices to
the apic_lvt_mask array. In later patches a LVT_CMCI will be added to
implement the Corrected Machine Check Interrupt signaling.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Jue Wang <juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220610171134.772566-3-juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Refactor APIC_VERSION so that the maximum number of LVT entries is
inserted at runtime rather than compile time. This will be used in a
subsequent commit to expose the LVT CMCI Register to VMs that support
Corrected Machine Check error counting/signaling
(IA32_MCG_CAP.MCG_CMCI_P=1).
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Jue Wang <juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220610171134.772566-2-juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The TLB flush before installing the newly-populated lower level
page table is unnecessary if the lower-level page table maps
the huge page identically. KVM knows it is if it did not reuse
an existing shadow page table, tell drop_large_spte() to skip
the flush in that case.
Extracted from a patch by David Matlack.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Add support for Eager Page Splitting pages that are mapped by nested
MMUs. Walk through the rmap first splitting all 1GiB pages to 2MiB
pages, and then splitting all 2MiB pages to 4KiB pages.
Note, Eager Page Splitting is limited to nested MMUs as a policy rather
than due to any technical reason (the sp->role.guest_mode check could
just be deleted and Eager Page Splitting would work correctly for all
shadow MMU pages). There is really no reason to support Eager Page
Splitting for tdp_mmu=N, since such support will eventually be phased
out, and there is no current use case supporting Eager Page Splitting on
hosts where TDP is either disabled or unavailable in hardware.
Furthermore, future improvements to nested MMU scalability may diverge
the code from the legacy shadow paging implementation. These
improvements will be simpler to make if Eager Page Splitting does not
have to worry about legacy shadow paging.
Splitting huge pages mapped by nested MMUs requires dealing with some
extra complexity beyond that of the TDP MMU:
(1) The shadow MMU has a limit on the number of shadow pages that are
allowed to be allocated. So, as a policy, Eager Page Splitting
refuses to split if there are KVM_MIN_FREE_MMU_PAGES or fewer
pages available.
(2) Splitting a huge page may end up re-using an existing lower level
shadow page tables. This is unlike the TDP MMU which always allocates
new shadow page tables when splitting.
(3) When installing the lower level SPTEs, they must be added to the
rmap which may require allocating additional pte_list_desc structs.
Case (2) is especially interesting since it may require a TLB flush,
unlike the TDP MMU which can fully split huge pages without any TLB
flushes. Specifically, an existing lower level page table may point to
even lower level page tables that are not fully populated, effectively
unmapping a portion of the huge page, which requires a flush. As of
this commit, a flush is always done always after dropping the huge page
and before installing the lower level page table.
This TLB flush could instead be delayed until the MMU lock is about to be
dropped, which would batch flushes for multiple splits. However these
flushes should be rare in practice (a huge page must be aliased in
multiple SPTEs and have been split for NX Huge Pages in only some of
them). Flushing immediately is simpler to plumb and also reduces the
chances of tripping over a CPU bug (e.g. see iTLB multihit).
[ This commit is based off of the original implementation of Eager Page
Splitting from Peter in Google's kernel from 2016. ]
Suggested-by: Peter Feiner <pfeiner@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-23-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Before allocating a child shadow page table, all callers check
whether the parent already points to a huge page and, if so, they
drop that SPTE. This is done by drop_large_spte().
However, dropping the large SPTE is really only necessary before the
sp is installed. While the sp is returned by kvm_mmu_get_child_sp(),
installing it happens later in __link_shadow_page(). Move the call
there instead of having it in each and every caller.
To ensure that the shadow page is not linked twice if it was present,
do _not_ opportunistically make kvm_mmu_get_child_sp() idempotent:
instead, return an error value if the shadow page already existed.
This is a bit more verbose, but clearer than NULL.
Finally, now that the drop_large_spte() name is not taken anymore,
remove the two underscores in front of __drop_large_spte().
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Currently KVM only zaps collapsible 4KiB SPTEs in the shadow MMU. This
is fine for now since KVM never creates intermediate huge pages during
dirty logging. In other words, KVM always replaces 1GiB pages directly
with 4KiB pages, so there is no reason to look for collapsible 2MiB
pages.
However, this will stop being true once the shadow MMU participates in
eager page splitting. During eager page splitting, each 1GiB is first
split into 2MiB pages and then those are split into 4KiB pages. The
intermediate 2MiB pages may be left behind if an error condition causes
eager page splitting to bail early.
No functional change intended.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-20-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Currently make_huge_page_split_spte() assumes execute permissions can be
granted to any 4K SPTE when splitting huge pages. This is true for the
TDP MMU but is not necessarily true for the shadow MMU, since KVM may be
shadowing a non-executable huge page.
To fix this, pass in the role of the child shadow page where the huge
page will be split and derive the execution permission from that. This
is correct because huge pages are always split with direct shadow page
and thus the shadow page role contains the correct access permissions.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-19-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Splitting huge pages requires allocating/finding shadow pages to replace
the huge page. Shadow pages are keyed, in part, off the guest access
permissions they are shadowing. For fully direct MMUs, there is no
shadowing so the access bits in the shadow page role are always ACC_ALL.
But during shadow paging, the guest can enforce whatever access
permissions it wants.
In particular, eager page splitting needs to know the permissions to use
for the subpages, but KVM cannot retrieve them from the guest page
tables because eager page splitting does not have a vCPU. Fortunately,
the guest access permissions are easy to cache whenever page faults or
FNAME(sync_page) update the shadow page tables; this is an extension of
the existing cache of the shadowed GFNs in the gfns array of the shadow
page. The access bits only take up 3 bits, which leaves 61 bits left
over for gfns, which is more than enough.
Now that the gfns array caches more information than just GFNs, rename
it to shadowed_translation.
While here, preemptively fix up the WARN_ON() that detects gfn
mismatches in direct SPs. The WARN_ON() was paired with a
pr_err_ratelimited(), which means that users could sometimes see the
WARN without the accompanying error message. Fix this by outputting the
error message as part of the WARN splat, and opportunistically make
them WARN_ONCE() because if these ever fire, they are all but guaranteed
to fire a lot and will bring down the kernel.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-18-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Update the page stats in __rmap_add() rather than at the call site. This
will avoid having to manually update page stats when splitting huge
pages in a subsequent commit.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-17-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Allow adding new entries to the rmap and linking shadow pages without a
struct kvm_vcpu pointer by moving the implementation of rmap_add() and
link_shadow_page() into inner helper functions.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-16-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Constify rmap_add()'s @slot parameter; it is simply passed on to
gfn_to_rmap(), which takes a const memslot.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-15-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Allow @vcpu to be NULL in kvm_mmu_find_shadow_page() (and its only
caller __kvm_mmu_get_shadow_page()). @vcpu is only required to sync
indirect shadow pages, so it's safe to pass in NULL when looking up
direct shadow pages.
This will be used for doing eager page splitting, which allocates direct
shadow pages from the context of a VM ioctl without access to a vCPU
pointer.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-14-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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kvm_mmu_find_shadow_page()
Get the kvm pointer from the caller, rather than deriving it from
vcpu->kvm, and plumb the kvm pointer all the way from
kvm_mmu_get_shadow_page(). With this change in place, the vcpu pointer
is only needed to sync indirect shadow pages. In other words,
__kvm_mmu_get_shadow_page() can now be used to get *direct* shadow pages
without a vcpu pointer. This enables eager page splitting, which needs
to allocate direct shadow pages during VM ioctls.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-13-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The vcpu pointer in kvm_mmu_alloc_shadow_page() is only used to get the
kvm pointer. So drop the vcpu pointer and just pass in the kvm pointer.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-12-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Refactor kvm_mmu_alloc_shadow_page() to receive the caches from which it
will allocate the various pieces of memory for shadow pages as a
parameter, rather than deriving them from the vcpu pointer. This will be
useful in a future commit where shadow pages are allocated during VM
ioctls for eager page splitting, and thus will use a different set of
caches.
Preemptively pull the caches out all the way to
kvm_mmu_get_shadow_page() since eager page splitting will not be calling
kvm_mmu_alloc_shadow_page() directly.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-11-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Move the code that write-protects newly-shadowed guest page tables into
account_shadowed(). This avoids a extra gfn-to-memslot lookup and is a
more logical place for this code to live. But most importantly, this
reduces kvm_mmu_alloc_shadow_page()'s reliance on having a struct
kvm_vcpu pointer, which will be necessary when creating new shadow pages
during VM ioctls for eager page splitting.
Note, it is safe to drop the role.level == PG_LEVEL_4K check since
account_shadowed() returns early if role.level > PG_LEVEL_4K.
No functional change intended.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-10-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Rename 2 functions:
kvm_mmu_get_page() -> kvm_mmu_get_shadow_page()
kvm_mmu_free_page() -> kvm_mmu_free_shadow_page()
This change makes it clear that these functions deal with shadow pages
rather than struct pages. It also aligns these functions with the naming
scheme for kvm_mmu_find_shadow_page() and kvm_mmu_alloc_shadow_page().
Prefer "shadow_page" over the shorter "sp" since these are core
functions and the line lengths aren't terrible.
No functional change intended.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-9-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Consolidate kvm_mmu_alloc_page() and kvm_mmu_alloc_shadow_page() under
the latter so that all shadow page allocation and initialization happens
in one place.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-8-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Decompose kvm_mmu_get_page() into separate helper functions to increase
readability and prepare for allocating shadow pages without a vcpu
pointer.
Specifically, pull the guts of kvm_mmu_get_page() into 2 helper
functions:
kvm_mmu_find_shadow_page() -
Walks the page hash checking for any existing mmu pages that match the
given gfn and role.
kvm_mmu_alloc_shadow_page()
Allocates and initializes an entirely new kvm_mmu_page. This currently
requries a vcpu pointer for allocation and looking up the memslot but
that will be removed in a future commit.
No functional change intended.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-7-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The quadrant is only used when gptes are 4 bytes, but
mmu_alloc_{direct,shadow}_roots() pass in a non-zero quadrant for PAE
page directories regardless. Make this less confusing by only passing in
a non-zero quadrant when it is actually necessary.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-6-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Instead of computing the shadow page role from scratch for every new
page, derive most of the information from the parent shadow page. This
eliminates the dependency on the vCPU root role to allocate shadow page
tables, and reduces the number of parameters to kvm_mmu_get_page().
Preemptively split out the role calculation to a separate function for
use in a following commit.
Note that when calculating the MMU root role, we can take
@role.passthrough, @role.direct, and @role.access directly from
@vcpu->arch.mmu->root_role. Only @role.level and @role.quadrant still
must be overridden for PAE page directories, when shadowing 32-bit
guest page tables with PAE page tables.
No functional change intended.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-5-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The "direct" argument is vcpu->arch.mmu->root_role.direct,
because unlike non-root page tables, it's impossible to have
a direct root in an indirect MMU. So just use that.
Suggested-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-4-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The parameter "direct" can either be true or false, and all of the
callers pass in a bool variable or true/false literal, so just use the
type bool.
No functional change intended.
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-3-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Commit fb58a9c345f6 ("KVM: x86/mmu: Optimize MMU page cache lookup for
fully direct MMUs") skipped the unsync checks and write flood clearing
for full direct MMUs. We can extend this further to skip the checks for
all direct shadow pages. Direct shadow pages in indirect MMUs (i.e.
shadow paging) are used when shadowing a guest huge page with smaller
pages. Such direct shadow pages, like their counterparts in fully direct
MMUs, are never marked unsynced or have a non-zero write-flooding count.
Checking sp->role.direct also generates better code than checking
direct_map because, due to register pressure, direct_map has to get
shoved onto the stack and then pulled back off.
No functional change intended.
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-2-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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In some cases, the NX hugepage mitigation for iTLB multihit is not
needed for all guests on a host. Allow disabling the mitigation on a
per-VM basis to avoid the performance hit of NX hugepages on trusted
workloads.
In order to disable NX hugepages on a VM, ensure that the userspace
actor has permission to reboot the system. Since disabling NX hugepages
would allow a guest to crash the system, it is similar to reboot
permissions.
Ideally, KVM would require userspace to prove it has access to KVM's
nx_huge_pages module param, e.g. so that userspace can opt out without
needing full reboot permissions. But getting access to the module param
file info is difficult because it is buried in layers of sysfs and module
glue. Requiring CAP_SYS_BOOT is sufficient for all known use cases.
Suggested-by: Jim Mattson <jmattson@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220613212523.3436117-9-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The braces around the KVM_CAP_XSAVE2 block also surround the
KVM_CAP_PMU_CAPABILITY block, likely the result of a merge issue. Simply
move the curly brace back to where it belongs.
Fixes: ba7bb663f5547 ("KVM: x86: Provide per VM capability for disabling PMU virtualization")
Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220613212523.3436117-8-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Add a quirk for KVM's behavior of emulating intercepted MONITOR/MWAIT
instructions a NOPs regardless of whether or not they are supported in
guest CPUID. KVM's current behavior was likely motiviated by a certain
fruity operating system that expects MONITOR/MWAIT to be supported
unconditionally and blindly executes MONITOR/MWAIT without first checking
CPUID. And because KVM does NOT advertise MONITOR/MWAIT to userspace,
that's effectively the default setup for any VMM that regurgitates
KVM_GET_SUPPORTED_CPUID to KVM_SET_CPUID2.
Note, this quirk interacts with KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT. The
behavior is actually desirable, as userspace VMMs that want to
unconditionally hide MONITOR/MWAIT from the guest can leave the
MISC_ENABLE quirk enabled.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220608224516.3788274-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Ignore host userspace writes of '0' to F15H_PERF_CTL MSRs KVM reports
in the MSR-to-save list, but the MSRs are ultimately unsupported. All
MSRs in said list must be writable by userspace, e.g. if userspace sends
the list back at KVM without filtering out the MSRs it doesn't need.
Note, reads of said MSRs already have the desired behavior.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220611005755.753273-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Ignore host userspace reads and writes of '0' to PEBS and BTS MSRs that
KVM reports in the MSR-to-save list, but the MSRs are ultimately
unsupported. All MSRs in said list must be writable by userspace, e.g.
if userspace sends the list back at KVM without filtering out the MSRs it
doesn't need.
Fixes: 8183a538cd95 ("KVM: x86/pmu: Add IA32_DS_AREA MSR emulation to support guest DS")
Fixes: 902caeb6841a ("KVM: x86/pmu: Add PEBS_DATA_CFG MSR emulation to support adaptive PEBS")
Fixes: c59a1f106f5c ("KVM: x86/pmu: Add IA32_PEBS_ENABLE MSR emulation for extended PEBS")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220611005755.753273-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Use vcpu_get_perf_capabilities() when querying MSR_IA32_PERF_CAPABILITIES
from the guest's perspective, e.g. to update the vPMU and to determine
which MSRs exist. If userspace ignores MSR_IA32_PERF_CAPABILITIES but
clear X86_FEATURE_PDCM, the guest should see '0'.
Fixes: 902caeb6841a ("KVM: x86/pmu: Add PEBS_DATA_CFG MSR emulation to support adaptive PEBS")
Fixes: c59a1f106f5c ("KVM: x86/pmu: Add IA32_PEBS_ENABLE MSR emulation for extended PEBS")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220611005755.753273-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Revert the hack to allow host-initiated accesses to all "PMU" MSRs,
as intel_is_valid_msr() returns true for _all_ MSRs, regardless of whether
or not it has a snowball's chance in hell of actually being a PMU MSR.
That mostly gets papered over by the actual get/set helpers only handling
MSRs that they knows about, except there's the minor detail that
kvm_pmu_{g,s}et_msr() eat reads and writes when the PMU is disabled.
I.e. KVM will happy allow reads and writes to _any_ MSR if the PMU is
disabled, either via module param or capability.
This reverts commit d1c88a4020567ba4da52f778bcd9619d87e4ea75.
Fixes: d1c88a402056 ("KVM: x86: always allow host-initiated writes to PMU MSRs")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220611005755.753273-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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!enable_pmu"
Eating reads and writes to all "PMU" MSRs when there is no PMU is wildly
broken as it results in allowing accesses to _any_ MSR on Intel CPUs
as intel_is_valid_msr() returns true for all host_initiated accesses.
A revert of commit d1c88a402056 ("KVM: x86: always allow host-initiated
writes to PMU MSRs") will soon follow.
This reverts commit 8e6a58e28b34e8d247e772159b8fa8f6bae39192.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220611005755.753273-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Do not clear manipulate MSR_IA32_PERF_CAPABILITIES in intel_pmu_refresh(),
i.e. give userspace full control over capability/read-only MSRs. KVM is
not a babysitter, it is userspace's responsiblity to provide a valid and
coherent vCPU model.
Attempting to "help" the guest by forcing a consistent model creates edge
cases, and ironicially leads to inconsistent behavior.
Example #1: KVM doesn't do intel_pmu_refresh() when userspace writes
the MSR.
Example #2: KVM doesn't clear the bits when the PMU is disabled, or when
there's no architectural PMU.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220611005755.753273-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Give userspace full control of the read-only bits in MISC_ENABLES, i.e.
do not modify bits on PMU refresh and do not preserve existing bits when
userspace writes MISC_ENABLES. With a few exceptions where KVM doesn't
expose the necessary controls to userspace _and_ there is a clear cut
association with CPUID, e.g. reserved CR4 bits, KVM does not own the vCPU
and should not manipulate the vCPU model on behalf of "dummy user space".
The argument that KVM is doing userspace a favor because "the order of
setting vPMU capabilities and MSR_IA32_MISC_ENABLE is not strictly
guaranteed" is specious, as attempting to configure MSRs on behalf of
userspace inevitably leads to edge cases precisely because KVM does not
prescribe a specific order of initialization.
Example #1: intel_pmu_refresh() consumes and modifies the vCPU's
MSR_IA32_PERF_CAPABILITIES, and so assumes userspace initializes config
MSRs before setting the guest CPUID model. If userspace sets CPUID
first, then KVM will mark PEBS as available when arch.perf_capabilities
is initialized with a non-zero PEBS format, thus creating a bad vCPU
model if userspace later disables PEBS by writing PERF_CAPABILITIES.
Example #2: intel_pmu_refresh() does not clear PERF_CAP_PEBS_MASK in
MSR_IA32_PERF_CAPABILITIES if there is no vPMU, making KVM inconsistent
in its desire to be consistent.
Example #3: intel_pmu_refresh() does not clear MSR_IA32_MISC_ENABLE_EMON
if KVM_SET_CPUID2 is called multiple times, first with a vPMU, then
without a vPMU. While slightly contrived, it's plausible a VMM could
reflect KVM's default vCPU and then operate on KVM's copy of CPUID to
later clear the vPMU settings, e.g. see KVM's selftests.
Example #4: Enumerating an Intel vCPU on an AMD host will not call into
intel_pmu_refresh() at any point, and so the BTS and PEBS "unavailable"
bits will be left clear, without any way for userspace to set them.
Keep the "R" behavior of the bit 7, "EMON available", for the guest.
Unlike the BTS and PEBS bits, which are fully "RO", the EMON bit can be
written with a different value, but that new value is ignored.
Cc: Like Xu <likexu@tencent.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
Message-Id: <20220611005755.753273-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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kfree can handle NULL pointer as its argument.
According to coccinelle isnullfree check, remove NULL check
before kfree operation.
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
Message-Id: <20220614133458.147314-1-dzm91@hust.edu.cn>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Move the check that restricts mapping huge pages into the guest to pfns
that are backed by refcounted 'struct page' memory into the helper that
actually "requires" a 'struct page', host_pfn_mapping_level(). In
addition to deduplicating code, moving the check to the helper eliminates
the subtle requirement that the caller check that the incoming pfn is
backed by a refcounted struct page, and as an added bonus avoids an extra
pfn_to_page() lookup.
Note, the is_error_noslot_pfn() check in kvm_mmu_hugepage_adjust() needs
to stay where it is, as it guards against dereferencing a NULL memslot in
the kvm_slot_dirty_track_enabled() that follows.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429010416.2788472-11-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Rename and refactor kvm_is_reserved_pfn() to kvm_pfn_to_refcounted_page()
to better reflect what KVM is actually checking, and to eliminate extra
pfn_to_page() lookups. The kvm_release_pfn_*() an kvm_try_get_pfn()
helpers in particular benefit from "refouncted" nomenclature, as it's not
all that obvious why KVM needs to get/put refcounts for some PG_reserved
pages (ZERO_PAGE and ZONE_DEVICE).
Add a comment to call out that the list of exceptions to PG_reserved is
all but guaranteed to be incomplete. The list has mostly been compiled
by people throwing noodles at KVM and finding out they stick a little too
well, e.g. the ZERO_PAGE's refcount overflowed and ZONE_DEVICE pages
didn't get freed.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429010416.2788472-10-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Operate on a 'struct page' instead of a pfn when checking if a page is a
ZONE_DEVICE page, and rename the helper accordingly. Generally speaking,
KVM doesn't actually care about ZONE_DEVICE memory, i.e. shouldn't do
anything special for ZONE_DEVICE memory. Rather, KVM wants to treat
ZONE_DEVICE memory like regular memory, and the need to identify
ZONE_DEVICE memory only arises as an exception to PG_reserved pages. In
other words, KVM should only ever check for ZONE_DEVICE memory after KVM
has already verified that there is a struct page associated with the pfn.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429010416.2788472-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Use kvm_vcpu_map() to get/pin the backing for vmcs12's APIC-access page,
there's no reason it has to be restricted to 'struct page' backing. The
APIC-access page actually doesn't need to be backed by anything, which is
ironically why it got left behind by the series which introduced
kvm_vcpu_map()[1]; the plan was to shove a dummy pfn into vmcs02[2], but
that code never got merged.
Switching the APIC-access page to kvm_vcpu_map() doesn't preclude using a
magic pfn in the future, and will allow a future patch to drop
kvm_vcpu_gpa_to_page().
[1] https://lore.kernel.org/all/1547026933-31226-1-git-send-email-karahmed@amazon.de
[2] https://lore.kernel.org/lkml/1543845551-4403-1-git-send-email-karahmed@amazon.de
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429010416.2788472-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Use common logic for computing PT_BASE_ADDR_MASK for 32-bit, 64-bit, and
EPT paging. Both PAGE_MASK and the new-common logic are supsersets of
what is actually needed for 32-bit paging. PAGE_MASK sets bits 63:12 and
the former GUEST_PT64_BASE_ADDR_MASK sets bits 51:12, so regardless of
which value is used, the result will always be bits 31:12.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220614233328.3896033-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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