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As documented in APM[1], LBR Virtualization must be enabled for SEV-ES
guests. Although KVM currently enforces LBRV for SEV-ES guests, there
are multiple issues with it:
o MSR_IA32_DEBUGCTLMSR is still intercepted. Since MSR_IA32_DEBUGCTLMSR
interception is used to dynamically toggle LBRV for performance reasons,
this can be fatal for SEV-ES guests. For ex SEV-ES guest on Zen3:
[guest ~]# wrmsr 0x1d9 0x4
KVM: entry failed, hardware error 0xffffffff
EAX=00000004 EBX=00000000 ECX=000001d9 EDX=00000000
Fix this by never intercepting MSR_IA32_DEBUGCTLMSR for SEV-ES guests.
No additional save/restore logic is required since MSR_IA32_DEBUGCTLMSR
is of swap type A.
o KVM will disable LBRV if userspace sets MSR_IA32_DEBUGCTLMSR before the
VMSA is encrypted. Fix this by moving LBRV enablement code post VMSA
encryption.
[1]: AMD64 Architecture Programmer's Manual Pub. 40332, Rev. 4.07 - June
2023, Vol 2, 15.35.2 Enabling SEV-ES.
https://bugzilla.kernel.org/attachment.cgi?id=304653
Fixes: 376c6d285017 ("KVM: SVM: Provide support for SEV-ES vCPU creation/loading")
Co-developed-by: Nikunj A Dadhania <[email protected]>
Signed-off-by: Nikunj A Dadhania <[email protected]>
Signed-off-by: Ravi Bangoria <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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As documented in APM[1], LBR Virtualization must be enabled for SEV-ES
guests. So, prevent SEV-ES guests when LBRV support is missing.
[1]: AMD64 Architecture Programmer's Manual Pub. 40332, Rev. 4.07 - June
2023, Vol 2, 15.35.2 Enabling SEV-ES.
https://bugzilla.kernel.org/attachment.cgi?id=304653
Fixes: 376c6d285017 ("KVM: SVM: Provide support for SEV-ES vCPU creation/loading")
Signed-off-by: Ravi Bangoria <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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KVM currently allows userspace to read/write MSRs even after the VMSA is
encrypted. This can cause unintentional issues if MSR access has side-
effects. For ex, while migrating a guest, userspace could attempt to
migrate MSR_IA32_DEBUGCTLMSR and end up unintentionally disabling LBRV on
the target. Fix this by preventing access to those MSRs which are context
switched via the VMSA, once the VMSA is encrypted.
Suggested-by: Sean Christopherson <[email protected]>
Signed-off-by: Nikunj A Dadhania <[email protected]>
Signed-off-by: Ravi Bangoria <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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All SNP APs are initially started using the APIC INIT/SIPI sequence in
the guest. This sequence moves the AP MP state from
KVM_MP_STATE_UNINITIALIZED to KVM_MP_STATE_RUNNABLE, so there is no need
to attempt the UNBLOCK.
As it is, the UNBLOCK support in SVM is only enabled when AVIC is
enabled. When AVIC is disabled, AP creation is still successful.
Remove the KVM_REQ_UNBLOCK request from the AP creation code and revert
the changes to the vcpu_unblocking() kvm_x86_ops path.
Signed-off-by: Tom Lendacky <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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The hook only handles cleanup work specific to SNP, e.g. RMP table
entries and flushing caches for encrypted guest memory. When run on a
non-SNP-enabled host (currently only possible using
KVM_X86_SW_PROTECTED_VM, e.g. via KVM selftests), the callback is a noop
and will WARN due to the RMP table not being present. It's actually
expected in this case that the RMP table wouldn't be present and that
the hook should be a noop, so drop the WARN_ONCE().
Reported-by: Sean Christopherson <[email protected]>
Closes: https://lore.kernel.org/kvm/[email protected]/
Fixes: 8eb01900b018 ("KVM: SEV: Implement gmem hook for invalidating private pages")
Suggested-by: Paolo Bonzini <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Currently there's a consistent pattern of always calling
host_rmp_make_shared() immediately after snp_page_reclaim(), so go ahead
and handle it automatically as part of snp_page_reclaim(). Also rename
it to kvm_rmp_make_shared() to more easily distinguish it as a
KVM-specific variant of the more generic rmp_make_shared() helper.
Suggested-by: Sean Christopherson <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Use KVM's snapshot of the host's XCR0 when stuffing SEV-ES host state
instead of reading XCR0 from hardware. XCR0 is only written during
boot, i.e. won't change while KVM is running (and KVM at large is hosed
if that doesn't hold true).
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sean Christopherson <[email protected]>
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Add "struct kvm_host_values kvm_host" to hold the various host values
that KVM snapshots during initialization. Bundling the host values into
a single struct simplifies adding new MSRs and other features with host
state/values that KVM cares about, and provides a one-stop shop. E.g.
adding a new value requires one line, whereas tracking each value
individual often requires three: declaration, definition, and export.
No functional change intended.
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sean Christopherson <[email protected]>
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When requesting an NMI window, WARN on vNMI support being enabled if and
only if NMIs are actually masked, i.e. if the vCPU is already handling an
NMI. KVM's ABI for NMIs that arrive simultanesouly (from KVM's point of
view) is to inject one NMI and pend the other. When using vNMI, KVM pends
the second NMI simply by setting V_NMI_PENDING, and lets the CPU do the
rest (hardware automatically sets V_NMI_BLOCKING when an NMI is injected).
However, if KVM can't immediately inject an NMI, e.g. because the vCPU is
in an STI shadow or is running with GIF=0, then KVM will request an NMI
window and trigger the WARN (but still function correctly).
Whether or not the GIF=0 case makes sense is debatable, as the intent of
KVM's behavior is to provide functionality that is as close to real
hardware as possible. E.g. if two NMIs are sent in quick succession, the
probability of both NMIs arriving in an STI shadow is infinitesimally low
on real hardware, but significantly larger in a virtual environment, e.g.
if the vCPU is preempted in the STI shadow. For GIF=0, the argument isn't
as clear cut, because the window where two NMIs can collide is much larger
in bare metal (though still small).
That said, KVM should not have divergent behavior for the GIF=0 case based
on whether or not vNMI support is enabled. And KVM has allowed
simultaneous NMIs with GIF=0 for over a decade, since commit 7460fb4a3400
("KVM: Fix simultaneous NMIs"). I.e. KVM's GIF=0 handling shouldn't be
modified without a *really* good reason to do so, and if KVM's behavior
were to be modified, it should be done irrespective of vNMI support.
Fixes: fa4c027a7956 ("KVM: x86: Add support for SVM's Virtual NMI")
Cc: [email protected]
Cc: Santosh Shukla <[email protected]>
Cc: Maxim Levitsky <[email protected]>
Signed-off-by: Sean Christopherson <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Add a module parameter than can be used to enable or disable the SEV-SNP
feature. Now that KVM contains the support for the SNP set the GHCB
hypervisor feature flag to indicate that SNP is supported.
Signed-off-by: Brijesh Singh <[email protected]>
Reviewed-by: Paolo Bonzini <[email protected]>
Signed-off-by: Ashish Kalra <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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With SNP/guest_memfd, private/encrypted memory should not be mappable,
and MMU notifications for HVA-mapped memory will only be relevant to
unencrypted guest memory. Therefore, the rationale behind issuing a
wbinvd_on_all_cpus() in sev_guest_memory_reclaimed() should not apply
for SNP guests and can be ignored.
Signed-off-by: Ashish Kalra <[email protected]>
Reviewed-by: Paolo Bonzini <[email protected]>
[mdr: Add some clarifications in commit]
Signed-off-by: Michael Roth <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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In the case of SEV-SNP, whether or not a 2MB page can be mapped via a
2MB mapping in the guest's nested page table depends on whether or not
any subpages within the range have already been initialized as private
in the RMP table. The existing mixed-attribute tracking in KVM is
insufficient here, for instance:
- gmem allocates 2MB page
- guest issues PVALIDATE on 2MB page
- guest later converts a subpage to shared
- SNP host code issues PSMASH to split 2MB RMP mapping to 4K
- KVM MMU splits NPT mapping to 4K
- guest later converts that shared page back to private
At this point there are no mixed attributes, and KVM would normally
allow for 2MB NPT mappings again, but this is actually not allowed
because the RMP table mappings are 4K and cannot be promoted on the
hypervisor side, so the NPT mappings must still be limited to 4K to
match this.
Implement a kvm_x86_ops.private_max_mapping_level() hook for SEV that
checks for this condition and adjusts the mapping level accordingly.
Reviewed-by: Paolo Bonzini <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Implement a platform hook to do the work of restoring the direct map
entries of gmem-managed pages and transitioning the corresponding RMP
table entries back to the default shared/hypervisor-owned state.
Signed-off-by: Michael Roth <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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This will handle the RMP table updates needed to put a page into a
private state before mapping it into an SEV-SNP guest.
Reviewed-by: Paolo Bonzini <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Add support for the SEV-SNP AP Creation NAE event. This allows SEV-SNP
guests to alter the register state of the APs on their own. This allows
the guest a way of simulating INIT-SIPI.
A new event, KVM_REQ_UPDATE_PROTECTED_GUEST_STATE, is created and used
so as to avoid updating the VMSA pointer while the vCPU is running.
For CREATE
The guest supplies the GPA of the VMSA to be used for the vCPU with
the specified APIC ID. The GPA is saved in the svm struct of the
target vCPU, the KVM_REQ_UPDATE_PROTECTED_GUEST_STATE event is added
to the vCPU and then the vCPU is kicked.
For CREATE_ON_INIT:
The guest supplies the GPA of the VMSA to be used for the vCPU with
the specified APIC ID the next time an INIT is performed. The GPA is
saved in the svm struct of the target vCPU.
For DESTROY:
The guest indicates it wishes to stop the vCPU. The GPA is cleared
from the svm struct, the KVM_REQ_UPDATE_PROTECTED_GUEST_STATE event is
added to vCPU and then the vCPU is kicked.
The KVM_REQ_UPDATE_PROTECTED_GUEST_STATE event handler will be invoked
as a result of the event or as a result of an INIT. If a new VMSA is to
be installed, the VMSA guest page is set as the VMSA in the vCPU VMCB
and the vCPU state is set to KVM_MP_STATE_RUNNABLE. If a new VMSA is not
to be installed, the VMSA is cleared in the vCPU VMCB and the vCPU state
is set to KVM_MP_STATE_HALTED to prevent it from being run.
Signed-off-by: Tom Lendacky <[email protected]>
Co-developed-by: Michael Roth <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Signed-off-by: Brijesh Singh <[email protected]>
Signed-off-by: Ashish Kalra <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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When SEV-SNP is enabled in the guest, the hardware places restrictions
on all memory accesses based on the contents of the RMP table. When
hardware encounters RMP check failure caused by the guest memory access
it raises the #NPF. The error code contains additional information on
the access type. See the APM volume 2 for additional information.
When using gmem, RMP faults resulting from mismatches between the state
in the RMP table vs. what the guest expects via its page table result
in KVM_EXIT_MEMORY_FAULTs being forwarded to userspace to handle. This
means the only expected case that needs to be handled in the kernel is
when the page size of the entry in the RMP table is larger than the
mapping in the nested page table, in which case a PSMASH instruction
needs to be issued to split the large RMP entry into individual 4K
entries so that subsequent accesses can succeed.
Signed-off-by: Brijesh Singh <[email protected]>
Co-developed-by: Michael Roth <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Signed-off-by: Ashish Kalra <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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SEV-SNP VMs can ask the hypervisor to change the page state in the RMP
table to be private or shared using the Page State Change NAE event
as defined in the GHCB specification version 2.
Forward these requests to userspace as KVM_EXIT_VMGEXITs, similar to how
it is done for requests that don't use a GHCB page.
As with the MSR-based page-state changes, use the existing
KVM_HC_MAP_GPA_RANGE hypercall format to deliver these requests to
userspace via KVM_EXIT_HYPERCALL.
Signed-off-by: Michael Roth <[email protected]>
Co-developed-by: Brijesh Singh <[email protected]>
Signed-off-by: Brijesh Singh <[email protected]>
Signed-off-by: Ashish Kalra <[email protected]>
Message-ID: <[email protected]>
Co-developed-by: Paolo Bonzini <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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SEV-SNP VMs can ask the hypervisor to change the page state in the RMP
table to be private or shared using the Page State Change MSR protocol
as defined in the GHCB specification.
When using gmem, private/shared memory is allocated through separate
pools, and KVM relies on userspace issuing a KVM_SET_MEMORY_ATTRIBUTES
KVM ioctl to tell the KVM MMU whether or not a particular GFN should be
backed by private memory or not.
Forward these page state change requests to userspace so that it can
issue the expected KVM ioctls. The KVM MMU will handle updating the RMP
entries when it is ready to map a private page into a guest.
Use the existing KVM_HC_MAP_GPA_RANGE hypercall format to deliver these
requests to userspace via KVM_EXIT_HYPERCALL.
Signed-off-by: Michael Roth <[email protected]>
Co-developed-by: Brijesh Singh <[email protected]>
Signed-off-by: Brijesh Singh <[email protected]>
Signed-off-by: Ashish Kalra <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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SEV-SNP guests are required to perform a GHCB GPA registration. Before
using a GHCB GPA for a vCPU the first time, a guest must register the
vCPU GHCB GPA. If hypervisor can work with the guest requested GPA then
it must respond back with the same GPA otherwise return -1.
On VMEXIT, verify that the GHCB GPA matches with the registered value.
If a mismatch is detected, then abort the guest.
Signed-off-by: Brijesh Singh <[email protected]>
Signed-off-by: Ashish Kalra <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Add a KVM_SEV_SNP_LAUNCH_FINISH command to finalize the cryptographic
launch digest which stores the measurement of the guest at launch time.
Also extend the existing SNP firmware data structures to support
disabling the use of Versioned Chip Endorsement Keys (VCEK) by guests as
part of this command.
While finalizing the launch flow, the code also issues the LAUNCH_UPDATE
SNP firmware commands to encrypt/measure the initial VMSA pages for each
configured vCPU, which requires setting the RMP entries for those pages
to private, so also add handling to clean up the RMP entries for these
pages whening freeing vCPUs during shutdown.
Signed-off-by: Brijesh Singh <[email protected]>
Co-developed-by: Michael Roth <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Signed-off-by: Harald Hoyer <[email protected]>
Signed-off-by: Ashish Kalra <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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A key aspect of a launching an SNP guest is initializing it with a
known/measured payload which is then encrypted into guest memory as
pre-validated private pages and then measured into the cryptographic
launch context created with KVM_SEV_SNP_LAUNCH_START so that the guest
can attest itself after booting.
Since all private pages are provided by guest_memfd, make use of the
kvm_gmem_populate() interface to handle this. The general flow is that
guest_memfd will handle allocating the pages associated with the GPA
ranges being initialized by each particular call of
KVM_SEV_SNP_LAUNCH_UPDATE, copying data from userspace into those pages,
and then the post_populate callback will do the work of setting the
RMP entries for these pages to private and issuing the SNP firmware
calls to encrypt/measure them.
For more information see the SEV-SNP specification.
Signed-off-by: Brijesh Singh <[email protected]>
Co-developed-by: Michael Roth <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Signed-off-by: Ashish Kalra <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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KVM_SEV_SNP_LAUNCH_START begins the launch process for an SEV-SNP guest.
The command initializes a cryptographic digest context used to construct
the measurement of the guest. Other commands can then at that point be
used to load/encrypt data into the guest's initial launch image.
For more information see the SEV-SNP specification.
Signed-off-by: Brijesh Singh <[email protected]>
Co-developed-by: Michael Roth <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Signed-off-by: Ashish Kalra <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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SEV-SNP builds upon existing SEV and SEV-ES functionality while adding
new hardware-based security protection. SEV-SNP adds strong memory
encryption and integrity protection to help prevent malicious
hypervisor-based attacks such as data replay, memory re-mapping, and
more, to create an isolated execution environment.
Define a new KVM_X86_SNP_VM type which makes use of these capabilities
and extend the KVM_SEV_INIT2 ioctl to support it. Also add a basic
helper to check whether SNP is enabled and set PFERR_PRIVATE_ACCESS for
private #NPFs so they are handled appropriately by KVM MMU.
Signed-off-by: Brijesh Singh <[email protected]>
Co-developed-by: Michael Roth <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Signed-off-by: Ashish Kalra <[email protected]>
Reviewed-by: Paolo Bonzini <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson into HEAD
LoongArch KVM changes for v6.10
1. Add ParaVirt IPI support.
2. Add software breakpoint support.
3. Add mmio trace events support.
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While the main additions from GHCB protocol version 1 to version 2
revolve mostly around SEV-SNP support, there are a number of changes
applicable to SEV-ES guests as well. Pluck a handful patches from the
SNP hypervisor patchset for GHCB-related changes that are also applicable
to SEV-ES. A KVM_SEV_INIT2 field lets userspace can control the maximum
GHCB protocol version advertised to guests and manage compatibility
across kernels/versions.
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The GHCB protocol version may be different from one guest to the next.
Add a field to track it for each KVM instance and extend KVM_SEV_INIT2
to allow it to be configured by userspace.
Now that all SEV-ES support for GHCB protocol version 2 is in place, go
ahead and default to it when creating SEV-ES guests through the new
KVM_SEV_INIT2 interface. Keep the older KVM_SEV_ES_INIT interface
restricted to GHCB protocol version 1.
Suggested-by: Sean Christopherson <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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GHCB version 2 adds support for a GHCB-based termination request that
a guest can issue when it reaches an error state and wishes to inform
the hypervisor that it should be terminated. Implement support for that
similarly to GHCB MSR-based termination requests that are already
available to SEV-ES guests via earlier versions of the GHCB protocol.
See 'Termination Request' in the 'Invoking VMGEXIT' section of the GHCB
specification for more details.
Signed-off-by: Michael Roth <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Version 2 of the GHCB specification introduced advertisement of features
that are supported by the Hypervisor.
Now that KVM supports version 2 of the GHCB specification, bump the
maximum supported protocol version.
Signed-off-by: Brijesh Singh <[email protected]>
Signed-off-by: Ashish Kalra <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Add support for AP Reset Hold being invoked using the GHCB MSR protocol,
available in version 2 of the GHCB specification.
Signed-off-by: Tom Lendacky <[email protected]>
Signed-off-by: Brijesh Singh <[email protected]>
Signed-off-by: Ashish Kalra <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Move the sanity check that hardware never sets bits that collide with KVM-
define synthetic bits from kvm_mmu_page_fault() to npf_interception(),
i.e. make the sanity check #NPF specific. The legacy #PF path already
WARNs if _any_ of bits 63:32 are set, and the error code that comes from
VMX's EPT Violatation and Misconfig is 100% synthesized (KVM morphs VMX's
EXIT_QUALIFICATION into error code flags).
Add a compile-time assert in the legacy #PF handler to make sure that KVM-
define flags are covered by its existing sanity check on the upper bits.
Opportunistically add a description of PFERR_IMPLICIT_ACCESS, since we
are removing the comment that defined it.
Signed-off-by: Sean Christopherson <[email protected]>
Reviewed-by: Kai Huang <[email protected]>
Reviewed-by: Binbin Wu <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Pull fix for SEV-SNP late disable bugs.
Signed-off-by: Paolo Bonzini <[email protected]>
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Signed-off-by: Paolo Bonzini <[email protected]>
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The DebugSwap feature of SEV-ES provides a way for confidential guests
to use data breakpoints. Its status is record in VMSA, and therefore
attestation signatures depend on whether it is enabled or not. In order
to avoid invalidating the signatures depending on the host machine, it
was disabled by default (see commit 5abf6dceb066, "SEV: disable SEV-ES
DebugSwap by default", 2024-03-09).
However, we now have a new API to create SEV VMs that allows enabling
DebugSwap based on what the user tells KVM to do, and we also changed the
legacy KVM_SEV_ES_INIT API to never enable DebugSwap. It is therefore
possible to re-enable the feature without breaking compatibility with
kernels that pre-date the introduction of DebugSwap, so go ahead.
Signed-off-by: Paolo Bonzini <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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The idea that no parameter would ever be necessary when enabling SEV or
SEV-ES for a VM was decidedly optimistic. In fact, in some sense it's
already a parameter whether SEV or SEV-ES is desired. Another possible
source of variability is the desired set of VMSA features, as that affects
the measurement of the VM's initial state and cannot be changed
arbitrarily by the hypervisor.
Create a new sub-operation for KVM_MEMORY_ENCRYPT_OP that can take a struct,
and put the new op to work by including the VMSA features as a field of the
struct. The existing KVM_SEV_INIT and KVM_SEV_ES_INIT use the full set of
supported VMSA features for backwards compatibility.
The struct also includes the usual bells and whistles for future
extensibility: a flags field that must be zero for now, and some padding
at the end.
Signed-off-by: Paolo Bonzini <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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SEV-ES allows passing custom contents for x87, SSE and AVX state into the VMSA.
Allow userspace to do that with the usual KVM_SET_XSAVE API and only mark
FPU contents as confidential after it has been copied and encrypted into
the VMSA.
Since the XSAVE state for AVX is the first, it does not need the
compacted-state handling of get_xsave_addr(). However, there are other
parts of XSAVE state in the VMSA that currently are not handled, and
the validation logic of get_xsave_addr() is pointless to duplicate
in KVM, so move get_xsave_addr() to public FPU API; it is really just
a facility to operate on XSAVE state and does not expose any internal
details of arch/x86/kernel/fpu.
Acked-by: Dave Hansen <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Signed-off-by: Paolo Bonzini <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Suggested-by: Sean Christopherson <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Right now, the set of features that are stored in the VMSA upon
initialization is fixed and depends on the module parameters for
kvm-amd.ko. However, the hypervisor cannot really change it at will
because the feature word has to match between the hypervisor and whatever
computes a measurement of the VMSA for attestation purposes.
Add a field to kvm_sev_info that holds the set of features to be stored
in the VMSA; and query it instead of referring to the module parameters.
Because KVM_SEV_INIT and KVM_SEV_ES_INIT accept no parameters, this
does not yet introduce any functional change, but it paves the way for
an API that allows customization of the features per-VM.
Signed-off-by: Paolo Bonzini <[email protected]>
Message-Id: <[email protected]>
Reviewed-by: Michael Roth <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Compute the set of features to be stored in the VMSA when KVM is
initialized; move it from there into kvm_sev_info when SEV is initialized,
and then into the initial VMSA.
The new variable can then be used to return the set of supported features
to userspace, via the KVM_GET_DEVICE_ATTR ioctl.
Signed-off-by: Paolo Bonzini <[email protected]>
Reviewed-by: Isaku Yamahata <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Stop compiling sev.c when CONFIG_KVM_AMD_SEV=n, as the number of #ifdefs
in sev.c is getting ridiculous, and having #ifdefs inside of SEV helpers
is quite confusing.
To minimize #ifdefs in code flows, #ifdef away only the kvm_x86_ops hooks
and the #VMGEXIT handler. Stubs are also restricted to functions that
check sev_enabled and to the destruction functions sev_free_cpu() and
sev_vm_destroy(), where the style of their callers is to leave checks
to the callers. Most call sites instead rely on dead code elimination
to take care of functions that are guarded with sev_guest() or
sev_es_guest().
Signed-off-by: Sean Christopherson <[email protected]>
Co-developed-by: Sean Christopherson <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Leave SEV and SEV_ES '0' in kvm_cpu_caps by default, and instead set them
in sev_set_cpu_caps() if SEV and SEV-ES support are fully enabled. Aside
from the fact that sev_set_cpu_caps() is wildly misleading when it *clears*
capabilities, this will allow compiling out sev.c without falsely
advertising SEV/SEV-ES support in KVM_GET_SUPPORTED_CPUID.
Signed-off-by: Sean Christopherson <[email protected]>
Reviewed-by: Michael Roth <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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Now that KVM uses the host save area to context switch RBP, i.e.
preserves RBP for the entirety of __svm_sev_es_vcpu_run(), create a stack
frame using the standared FRAME_{BEGIN,END} macros.
Note, __svm_sev_es_vcpu_run() is subtly not a leaf function as it can call
into ibpb_feature() via UNTRAIN_RET_VM.
Reviewed-by: Tom Lendacky <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sean Christopherson <[email protected]>
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Use the host save area to preserve volatile registers that are used in
__svm_sev_es_vcpu_run() to access function parameters after #VMEXIT.
Like saving/restoring non-volatile registers, there's no reason not to
take advantage of hardware restoring registers on #VMEXIT, as doing so
shaves a few instructions and the save area is going to be accessed no
matter what.
Converting all register save/restore code to use the host save area also
make it easier to follow the SEV-ES VMRUN flow in its entirety, as
opposed to having a mix of stack-based versus host save area save/restore.
Add a parameter to RESTORE_HOST_SPEC_CTRL_BODY so that the SEV-ES path
doesn't need to write @spec_ctrl_intercepted to memory just to play nice
with the common macro.
Reviewed-by: Tom Lendacky <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sean Christopherson <[email protected]>
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Use the host save area to save/restore non-volatile (callee-saved)
registers in __svm_sev_es_vcpu_run() to take advantage of hardware loading
all registers from the save area on #VMEXIT. KVM still needs to save the
registers it wants restored, but the loads are handled automatically by
hardware.
Aside from less assembly code, letting hardware do the restoration means
stack frames are preserved for the entirety of __svm_sev_es_vcpu_run().
Opportunistically add a comment to call out why @svm needs to be saved
across VMRUN->#VMEXIT, as it's not easy to decipher that from the macro
hell.
Cc: Tom Lendacky <[email protected]>
Cc: Michael Roth <[email protected]>
Cc: Alexey Kardashevskiy <[email protected]>
Reviewed-by: Tom Lendacky <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sean Christopherson <[email protected]>
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POP @spec_ctrl_intercepted into RAX instead of RBX when discarding it from
the stack so that __svm_sev_es_vcpu_run() doesn't modify any non-volatile
registers. __svm_sev_es_vcpu_run() doesn't return a value, and RAX is
already are clobbered multiple times in the #VMEXIT path.
This will allowing using the host save area to save/restore non-volatile
registers in __svm_sev_es_vcpu_run().
Reviewed-by: Tom Lendacky <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sean Christopherson <[email protected]>
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Drop 32-bit "support" from __svm_sev_es_vcpu_run(), as SEV/SEV-ES firmly
64-bit only. The "support" was purely the result of bad copy+paste from
__svm_vcpu_run(), which in turn was slightly less bad copy+paste from
__vmx_vcpu_run().
Opportunistically convert to unadulterated register accesses so that it's
easier (but still not easy) to follow which registers hold what arguments,
and when.
Reviewed-by: Tom Lendacky <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sean Christopherson <[email protected]>
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Compile (and link) __svm_sev_es_vcpu_run() if and only if SEV support is
actually enabled. This will allow dropping non-existent 32-bit "support"
from __svm_sev_es_vcpu_run() without causing undue confusion.
Intentionally don't provide a stub (but keep the declaration), as any sane
compiler, even with things like KASAN enabled, should eliminate the call
to __svm_sev_es_vcpu_run() since sev_es_guest() unconditionally returns
"false" if CONFIG_KVM_AMD_SEV=n.
Reviewed-by: Tom Lendacky <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sean Christopherson <[email protected]>
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Unconditionally create a stack frame in __svm_vcpu_run() to play nice with
unwinding via frame pointers, at least until the point where RBP is loaded
with the guest's value. Don't bother conditioning the code on
CONFIG_FRAME_POINTER=y, as RBP needs to be saved and restored anyways (due
to it being clobbered with the guest's value); omitting the "MOV RSP, RBP"
is not worth the extra #ifdef.
Creating a stack frame will allow removing the OBJECT_FILES_NON_STANDARD
tag from vmenter.S once __svm_sev_es_vcpu_run() is fixed to not stomp all
over RBP for no reason.
Reviewed-by: Tom Lendacky <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sean Christopherson <[email protected]>
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Remove KVM's unnecessary zeroing of memory when allocating the pages array
in sev_pin_memory() via __vmalloc(), as the array is only used to hold
kernel pointers. The kmalloc() path for "small" regions doesn't zero the
array, and if KVM leaks state and/or accesses uninitialized data, then the
kernel has bigger problems.
Signed-off-by: Christophe JAILLET <[email protected]>
Link: https://lore.kernel.org/r/c7619a3d3cbb36463531a7c73ccbde9db587986c.1710004509.git.christophe.jaillet@wanadoo.fr
[sean: massage changelog]
Signed-off-by: Sean Christopherson <[email protected]>
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We want to fix:
0e110732473e ("x86/retpoline: Do the necessary fixup to the Zen3/4 srso return thunk for !SRSO")
So merge in Linus's latest into x86/urgent to have it available.
Signed-off-by: Ingo Molnar <[email protected]>
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