GMET allows page table entries to be created with U=0 in NPT.
However, when GMET=1 U=0 only affects execution, not reads or
writes. Ignore user faults on non-fetch accesses for NPT GMET.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/include/asm/kvm_host.h | 2 ++
arch/x86/kvm/mmu.h | 3 ++-
arch/x86/kvm/mmu/mmu.c | 19 +++++++++++++------
arch/x86/kvm/svm/nested.c | 3 ++-
4 files changed, 19 insertions(+), 8 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index df46ee605b9b..2a26c8fe3f4b 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -369,6 +369,8 @@ union kvm_mmu_page_role {
* cr4_smep is also set for EPT MBEC. Because it affects
* which pages are considered non-present (bit 10 additionally
* must be zero if MBEC is on) it has to be in the base role.
+ * It also has to be in the base role for AMD GMET because
+ * kernel-executable pages need to have U=0 with GMET enabled.
*/
unsigned cr4_smep:1;
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index fa1942b126fb..ddca3e3e4eb2 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -90,7 +90,8 @@ void kvm_mmu_set_ept_masks(bool has_ad_bits, bool has_mbec);
void kvm_init_mmu(struct kvm_vcpu *vcpu);
void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0,
- unsigned long cr4, u64 efer, gpa_t nested_cr3);
+ unsigned long cr4, u64 efer, gpa_t nested_cr3,
+ u64 nested_ctl);
void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
int huge_page_level, bool accessed_dirty,
bool mbec, gpa_t new_eptp);
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 94d7e39a9417..d9eb059d24de 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -55,6 +55,7 @@
#include <asm/io.h>
#include <asm/set_memory.h>
#include <asm/spec-ctrl.h>
+#include <asm/svm.h>
#include <asm/vmx.h>
#include "trace.h"
@@ -5553,7 +5554,7 @@ reset_ept_shadow_zero_bits_mask(struct kvm_mmu *context, bool execonly)
(14 & (access) ? 1 << 14 : 0) | \
(15 & (access) ? 1 << 15 : 0))
-static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept)
+static void update_permission_bitmask(struct kvm_mmu *mmu, bool tdp, bool ept)
{
unsigned byte;
@@ -5614,7 +5615,12 @@ static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept)
/* Faults from kernel mode accesses to user pages */
u16 kf = (pfec & PFERR_USER_MASK) ? 0 : u;
- uf = (pfec & PFERR_USER_MASK) ? (u16)~u : 0;
+ /*
+ * For NPT GMET, U=0 does not affect reads and writes. Fetches
+ * are handled below via cr4_smep.
+ */
+ if (!(tdp && cr4_smep))
+ uf = (pfec & PFERR_USER_MASK) ? (u16)~u : 0;
if (efer_nx)
ff = (pfec & PFERR_FETCH_MASK) ? (u16)~x : 0;
@@ -5725,7 +5731,7 @@ static void reset_guest_paging_metadata(struct kvm_vcpu *vcpu,
return;
reset_guest_rsvds_bits_mask(vcpu, mmu);
- update_permission_bitmask(mmu, false);
+ update_permission_bitmask(mmu, mmu == &vcpu->arch.guest_mmu, false);
update_pkru_bitmask(mmu);
}
@@ -5921,7 +5927,8 @@ static void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu,
}
void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0,
- unsigned long cr4, u64 efer, gpa_t nested_cr3)
+ unsigned long cr4, u64 efer, gpa_t nested_cr3,
+ u64 nested_ctl)
{
struct kvm_mmu *context = &vcpu->arch.guest_mmu;
struct kvm_mmu_role_regs regs = {
@@ -5934,7 +5941,7 @@ void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0,
/* NPT requires CR0.PG=1. */
WARN_ON_ONCE(cpu_role.base.direct || !cpu_role.base.guest_mode);
- cpu_role.base.cr4_smep = false;
+ cpu_role.base.cr4_smep = (nested_ctl & SVM_NESTED_CTL_GMET_ENABLE) != 0;
root_role = cpu_role.base;
root_role.level = kvm_mmu_get_tdp_level(vcpu);
@@ -5992,7 +5999,7 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
context->gva_to_gpa = ept_gva_to_gpa;
context->sync_spte = ept_sync_spte;
- update_permission_bitmask(context, true);
+ update_permission_bitmask(context, true, true);
context->pkru_mask = 0;
reset_rsvds_bits_mask_ept(vcpu, context, execonly, huge_page_level);
reset_ept_shadow_zero_bits_mask(context, execonly);
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index b36c33255bed..99edcca7ee64 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -95,7 +95,8 @@ static void nested_svm_init_mmu_context(struct kvm_vcpu *vcpu)
*/
kvm_init_shadow_npt_mmu(vcpu, X86_CR0_PG, svm->vmcb01.ptr->save.cr4,
svm->vmcb01.ptr->save.efer,
- svm->nested.ctl.nested_cr3);
+ svm->nested.ctl.nested_cr3,
+ svm->nested.ctl.nested_ctl);
vcpu->arch.mmu->get_guest_pgd = nested_svm_get_tdp_cr3;
vcpu->arch.mmu->get_pdptr = nested_svm_get_tdp_pdptr;
vcpu->arch.mmu->inject_page_fault = nested_svm_inject_npf_exit;
--
2.53.0