diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2024-05-12 03:18:44 -0400 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2024-05-12 03:18:44 -0400 |
| commit | 7d41e24da29a83acc52a78a68aa515dd76e41cc1 (patch) | |
| tree | 4ab35b9e1c69ff5b454844a0df16ee483ffc1f2d /arch/x86/kvm/cpuid.c | |
| parent | 5a1c72e07e830dda424f2929332a1435c9736da3 (diff) | |
| parent | 51937f2aae186e335175dde78279aaf0cb5e72ae (diff) | |
Merge tag 'kvm-x86-misc-6.10' of https://github.com/kvm-x86/linux into HEAD
KVM x86 misc changes for 6.10:
- Advertise the max mappable GPA in the "guest MAXPHYADDR" CPUID field, which
is unused by hardware, so that KVM can communicate its inability to map GPAs
that set bits 51:48 due to lack of 5-level paging. Guest firmware is
expected to use the information to safely remap BARs in the uppermost GPA
space, i.e to avoid placing a BAR at a legal, but unmappable, GPA.
- Use vfree() instead of kvfree() for allocations that always use vcalloc()
or __vcalloc().
- Don't completely ignore same-value writes to immutable feature MSRs, as
doing so results in KVM failing to reject accesses to MSR that aren't
supposed to exist given the vCPU model and/or KVM configuration.
- Don't mark APICv as being inhibited due to ABSENT if APICv is disabled
KVM-wide to avoid confusing debuggers (KVM will never bother clearing the
ABSENT inhibit, even if userspace enables in-kernel local APIC).
Diffstat (limited to 'arch/x86/kvm/cpuid.c')
| -rw-r--r-- | arch/x86/kvm/cpuid.c | 41 |
1 files changed, 31 insertions, 10 deletions
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 1851b3870a9c..f2f2be5d1141 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -1232,9 +1232,22 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) entry->eax = entry->ebx = entry->ecx = 0; break; case 0x80000008: { - unsigned g_phys_as = (entry->eax >> 16) & 0xff; - unsigned virt_as = max((entry->eax >> 8) & 0xff, 48U); - unsigned phys_as = entry->eax & 0xff; + /* + * GuestPhysAddrSize (EAX[23:16]) is intended for software + * use. + * + * KVM's ABI is to report the effective MAXPHYADDR for the + * guest in PhysAddrSize (phys_as), and the maximum + * *addressable* GPA in GuestPhysAddrSize (g_phys_as). + * + * GuestPhysAddrSize is valid if and only if TDP is enabled, + * in which case the max GPA that can be addressed by KVM may + * be less than the max GPA that can be legally generated by + * the guest, e.g. if MAXPHYADDR>48 but the CPU doesn't + * support 5-level TDP. + */ + unsigned int virt_as = max((entry->eax >> 8) & 0xff, 48U); + unsigned int phys_as, g_phys_as; /* * If TDP (NPT) is disabled use the adjusted host MAXPHYADDR as @@ -1242,16 +1255,24 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) * reductions in MAXPHYADDR for memory encryption affect shadow * paging, too. * - * If TDP is enabled but an explicit guest MAXPHYADDR is not - * provided, use the raw bare metal MAXPHYADDR as reductions to - * the HPAs do not affect GPAs. + * If TDP is enabled, use the raw bare metal MAXPHYADDR as + * reductions to the HPAs do not affect GPAs. The max + * addressable GPA is the same as the max effective GPA, except + * that it's capped at 48 bits if 5-level TDP isn't supported + * (hardware processes bits 51:48 only when walking the fifth + * level page table). */ - if (!tdp_enabled) - g_phys_as = boot_cpu_data.x86_phys_bits; - else if (!g_phys_as) + if (!tdp_enabled) { + phys_as = boot_cpu_data.x86_phys_bits; + g_phys_as = 0; + } else { + phys_as = entry->eax & 0xff; g_phys_as = phys_as; + if (kvm_mmu_get_max_tdp_level() < 5) + g_phys_as = min(g_phys_as, 48); + } - entry->eax = g_phys_as | (virt_as << 8); + entry->eax = phys_as | (virt_as << 8) | (g_phys_as << 16); entry->ecx &= ~(GENMASK(31, 16) | GENMASK(11, 8)); entry->edx = 0; cpuid_entry_override(entry, CPUID_8000_0008_EBX); |