diff options
| author | Yan Zhao <yan.y.zhao@intel.com> | 2023-07-14 14:50:06 +0800 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2023-10-09 14:34:57 -0700 |
| commit | 1affe455d66de4e1743514afdeb99cb598a25aa2 (patch) | |
| tree | 8eb07edc00105cd7a46986ea50fe5c8b1251d8fb /arch/x86/kvm/mmu | |
| parent | 5804c19b80bf625c6a9925317f845e497434d6d3 (diff) | |
KVM: x86/mmu: Add helpers to return if KVM honors guest MTRRs
Add helpers to check if KVM honors guest MTRRs instead of open coding the
logic in kvm_tdp_page_fault(). Future fixes and cleanups will also need
to determine if KVM should honor guest MTRRs, e.g. for CR0.CD toggling and
and non-coherent DMA transitions.
Provide an inner helper, __kvm_mmu_honors_guest_mtrrs(), so that KVM can
check if guest MTRRs were honored when stopping non-coherent DMA.
Note, there is no need to explicitly check that TDP is enabled, KVM clears
shadow_memtype_mask when TDP is disabled, i.e. it's non-zero if and only
if EPT is enabled.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Link: https://lore.kernel.org/r/20230714065006.20201-1-yan.y.zhao@intel.com
Link: https://lore.kernel.org/r/20230714065043.20258-1-yan.y.zhao@intel.com
[sean: squash into a one patch, drop explicit TDP check massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'arch/x86/kvm/mmu')
| -rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index f7901cb4d2fa..5d3dc7119e57 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4479,21 +4479,28 @@ out_unlock: } #endif -int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) +bool __kvm_mmu_honors_guest_mtrrs(bool vm_has_noncoherent_dma) { /* - * If the guest's MTRRs may be used to compute the "real" memtype, - * restrict the mapping level to ensure KVM uses a consistent memtype - * across the entire mapping. If the host MTRRs are ignored by TDP - * (shadow_memtype_mask is non-zero), and the VM has non-coherent DMA - * (DMA doesn't snoop CPU caches), KVM's ABI is to honor the memtype - * from the guest's MTRRs so that guest accesses to memory that is - * DMA'd aren't cached against the guest's wishes. + * If host MTRRs are ignored (shadow_memtype_mask is non-zero), and the + * VM has non-coherent DMA (DMA doesn't snoop CPU caches), KVM's ABI is + * to honor the memtype from the guest's MTRRs so that guest accesses + * to memory that is DMA'd aren't cached against the guest's wishes. * * Note, KVM may still ultimately ignore guest MTRRs for certain PFNs, * e.g. KVM will force UC memtype for host MMIO. */ - if (shadow_memtype_mask && kvm_arch_has_noncoherent_dma(vcpu->kvm)) { + return vm_has_noncoherent_dma && shadow_memtype_mask; +} + +int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) +{ + /* + * If the guest's MTRRs may be used to compute the "real" memtype, + * restrict the mapping level to ensure KVM uses a consistent memtype + * across the entire mapping. + */ + if (kvm_mmu_honors_guest_mtrrs(vcpu->kvm)) { for ( ; fault->max_level > PG_LEVEL_4K; --fault->max_level) { int page_num = KVM_PAGES_PER_HPAGE(fault->max_level); gfn_t base = gfn_round_for_level(fault->gfn, |