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KVM: x86/mmu: store shadow EFER.NX in the MMU role

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Now that the MMU role is separate from the CPU role, it can be a
truthful description of the format of the shadow pages.  This includes
whether the shadow pages use the NX bit; so force the efer_nx field
of the MMU role when TDP is disabled, and remove the hardcoding it in
the callers of reset_shadow_zero_bits_mask.

In fact, the initialization of reserved SPTE bits can now be made common
to shadow paging and shadow NPT; move it to shadow_mmu_init_context.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2022-02-10 07:33:38 -05:00
parent f417e1459a
commit 362505deb8
1 changed files with 12 additions and 11 deletions
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23
arch/x86/kvm/mmu/mmu.c
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@ -4473,16 +4473,6 @@ static inline u64 reserved_hpa_bits(void)
static void reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu,
struct kvm_mmu *context)
{
/*
* KVM uses NX when TDP is disabled to handle a variety of scenarios,
* notably for huge SPTEs if iTLB multi-hit mitigation is enabled and
* to generate correct permissions for CR0.WP=0/CR4.SMEP=1/EFER.NX=0.
* The iTLB multi-hit workaround can be toggled at any time, so assume
* NX can be used by any non-nested shadow MMU to avoid having to reset
* MMU contexts. Note, KVM forces EFER.NX=1 when TDP is disabled.
*/
bool uses_nx = is_efer_nx(context) || !tdp_enabled;
/* @amd adds a check on bit of SPTEs, which KVM shouldn't use anyways. */
bool is_amd = true;
/* KVM doesn't use 2-level page tables for the shadow MMU. */
@ -4494,7 +4484,8 @@ static void reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu,
shadow_zero_check = &context->shadow_zero_check;
__reset_rsvds_bits_mask(shadow_zero_check, reserved_hpa_bits(),
context->shadow_root_level, uses_nx,
context->shadow_root_level,
context->mmu_role.base.efer_nx,
guest_can_use_gbpages(vcpu), is_pse, is_amd);
if (!shadow_me_mask)
@ -4858,6 +4849,16 @@ kvm_calc_shadow_mmu_root_page_role(struct kvm_vcpu *vcpu,
else
role.base.level = PT64_ROOT_4LEVEL;
/*
* KVM forces EFER.NX=1 when TDP is disabled, reflect it in the MMU role.
* KVM uses NX when TDP is disabled to handle a variety of scenarios,
* notably for huge SPTEs if iTLB multi-hit mitigation is enabled and
* to generate correct permissions for CR0.WP=0/CR4.SMEP=1/EFER.NX=0.
* The iTLB multi-hit workaround can be toggled at any time, so assume
* NX can be used by any non-nested shadow MMU to avoid having to reset
* MMU contexts.
*/
role.base.efer_nx = true;
return role;
}