[PATCH v10 036/108] KVM: TDX: Enable mmio spte caching always for TDX

isaku.yamahata
2022-10-30T06:26:36Z

From: Isaku Yamahata <isaku.yamahata@intel.com>

TDX needs to set shared spte for MMIO GFN to !SUPPRES_VE_BIT | !RWX so that
guest TD can get #VE and then issue TDG.VP.VMCALL<MMIO>. Enable mmio
caching always for TDX irrelevant the module parameter enable_mmio_caching.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
arch/x86/kvm/mmu/mmu.c | 3 ++-
arch/x86/kvm/mmu/spte.h | 2 +-
arch/x86/kvm/mmu/tdp_mmu.c | 7 +++++++
3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 0d3fa29ccccc..9098f77cdaa4 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3229,7 +3229,8 @@ static int handle_abnormal_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fau
* and only if L1's MAXPHYADDR is inaccurate with respect to
* the hardware's).
*/
- if (unlikely(!enable_mmio_caching) ||
+ if (unlikely(!enable_mmio_caching &&
+ !kvm_gfn_shared_mask(vcpu->kvm)) ||
unlikely(fault->gfn > kvm_mmu_max_gfn()))
return RET_PF_EMULATE;
}
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index 82f0d5c08b77..fecfdcb5f321 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -244,7 +244,7 @@ extern u64 __read_mostly shadow_nonpresent_or_rsvd_lower_gfn_mask;
static inline bool is_mmio_spte(struct kvm *kvm, u64 spte)
{
return (spte & shadow_mmio_mask) == kvm->arch.shadow_mmio_value &&
- likely(enable_mmio_caching);
+ likely(enable_mmio_caching || kvm_gfn_shared_mask(kvm));
}

static inline bool is_shadow_present_pte(u64 pte)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index e07f14351d14..3325633b1cb5 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1875,6 +1875,13 @@ int kvm_tdp_mmu_get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes,

*root_level = vcpu->arch.mmu->root_role.level;

+ /*
+ * mmio page fault isn't supported for protected guest because
+ * instructions in protected guest memory can't be parsed by VMM.
+ */
+ if (WARN_ON_ONCE(kvm_gfn_shared_mask(vcpu->kvm)))
+ return leaf;
+
tdp_mmu_for_each_pte(iter, mmu, gfn, gfn + 1) {
leaf = iter.level;
sptes[leaf] = iter.old_spte;
--
2.25.1