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KVM: x86/mmu: Use MMU's roles to compute last non-leaf level

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Use the MMU's role to get CR4.PSE when determining the last level at
which the guest _cannot_ create a non-leaf PTE, i.e. cannot create a
huge page.

Note, the existing logic is arguably wrong when considering 5-level
paging and the case where 1gb pages aren't supported.  In practice, the
logic is confusing but not broken, because except for 32-bit non-PAE
paging, bit 7 (_PAGE_PSE) bit is reserved when a huge page isn't supported at
that level.  I.e. setting bit 7 will terminate the guest walk one way or
another.  Furthermore, last_nonleaf_level is only consulted after KVM has
verified there are no reserved bits set.

All that confusion will be addressed in a future patch by dropping
last_nonleaf_level entirely.  For now, massage the code to continue the
march toward using mmu_role for (almost) all MMU computations.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210622175739.3610207-35-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-06-22 10:57:19 -07:00 committed by Paolo Bonzini
parent 2e4c06618d
commit b67a93a87e
1 changed files with 6 additions and 6 deletions
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12
arch/x86/kvm/mmu/mmu.c
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@ -4504,12 +4504,12 @@ static void update_pkru_bitmask(struct kvm_mmu *mmu)
}
}
static void update_last_nonleaf_level(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu)
static void update_last_nonleaf_level(struct kvm_mmu *mmu)
{
unsigned root_level = mmu->root_level;
mmu->last_nonleaf_level = root_level;
if (root_level == PT32_ROOT_LEVEL && is_pse(vcpu))
if (root_level == PT32_ROOT_LEVEL && is_cr4_pse(mmu))
mmu->last_nonleaf_level++;
}
@ -4666,7 +4666,7 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
update_permission_bitmask(context, false);
update_pkru_bitmask(context);
update_last_nonleaf_level(vcpu, context);
update_last_nonleaf_level(context);
reset_tdp_shadow_zero_bits_mask(vcpu, context);
}
@ -4724,7 +4724,7 @@ static void shadow_mmu_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *conte
reset_rsvds_bits_mask(vcpu, context);
update_permission_bitmask(context, false);
update_pkru_bitmask(context);
update_last_nonleaf_level(vcpu, context);
update_last_nonleaf_level(context);
}
context->shadow_root_level = new_role.base.level;
@ -4831,7 +4831,7 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
context->direct_map = false;
update_permission_bitmask(context, true);
update_last_nonleaf_level(vcpu, context);
update_last_nonleaf_level(context);
update_pkru_bitmask(context);
reset_rsvds_bits_mask_ept(vcpu, context, execonly);
reset_ept_shadow_zero_bits_mask(vcpu, context, execonly);
@ -4929,7 +4929,7 @@ static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu)
update_permission_bitmask(g_context, false);
update_pkru_bitmask(g_context);
update_last_nonleaf_level(vcpu, g_context);
update_last_nonleaf_level(g_context);
}
void kvm_init_mmu(struct kvm_vcpu *vcpu)