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kvm: x86: Support resetting the MMU context without resetting roots
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This adds support for re-initializing the MMU context in a different
mode while preserving the active root_hpa and the prev_root.

Signed-off-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Junaid Shahid authored and Paolo Bonzini committed Aug 6, 2018
1 parent 0aab33e commit 1c53da3
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Showing 2 changed files with 10 additions and 17 deletions.
26 changes: 9 additions & 17 deletions arch/x86/kvm/mmu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4032,8 +4032,6 @@ static void nonpaging_init_context(struct kvm_vcpu *vcpu,
context->update_pte = nonpaging_update_pte;
context->root_level = 0;
context->shadow_root_level = PT32E_ROOT_LEVEL;
context->root_hpa = INVALID_PAGE;
context->prev_root = KVM_MMU_ROOT_INFO_INVALID;
context->direct_map = true;
context->nx = false;
}
Expand Down Expand Up @@ -4568,8 +4566,6 @@ static void paging64_init_context_common(struct kvm_vcpu *vcpu,
context->invlpg = paging64_invlpg;
context->update_pte = paging64_update_pte;
context->shadow_root_level = level;
context->root_hpa = INVALID_PAGE;
context->prev_root = KVM_MMU_ROOT_INFO_INVALID;
context->direct_map = false;
}

Expand Down Expand Up @@ -4599,8 +4595,6 @@ static void paging32_init_context(struct kvm_vcpu *vcpu,
context->invlpg = paging32_invlpg;
context->update_pte = paging32_update_pte;
context->shadow_root_level = PT32E_ROOT_LEVEL;
context->root_hpa = INVALID_PAGE;
context->prev_root = KVM_MMU_ROOT_INFO_INVALID;
context->direct_map = false;
}

Expand Down Expand Up @@ -4636,8 +4630,6 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
context->invlpg = nonpaging_invlpg;
context->update_pte = nonpaging_update_pte;
context->shadow_root_level = kvm_x86_ops->get_tdp_level(vcpu);
context->root_hpa = INVALID_PAGE;
context->prev_root = KVM_MMU_ROOT_INFO_INVALID;
context->direct_map = true;
context->set_cr3 = kvm_x86_ops->set_tdp_cr3;
context->get_cr3 = get_cr3;
Expand Down Expand Up @@ -4703,8 +4695,6 @@ void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu)
{
struct kvm_mmu *context = &vcpu->arch.mmu;

MMU_WARN_ON(VALID_PAGE(context->root_hpa));

if (!is_paging(vcpu))
nonpaging_init_context(vcpu, context);
else if (is_long_mode(vcpu))
Expand Down Expand Up @@ -4741,8 +4731,6 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
union kvm_mmu_page_role root_page_role =
kvm_calc_shadow_ept_root_page_role(vcpu, accessed_dirty);

MMU_WARN_ON(VALID_PAGE(context->root_hpa));

context->shadow_root_level = PT64_ROOT_4LEVEL;

context->nx = true;
Expand All @@ -4753,8 +4741,6 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
context->invlpg = ept_invlpg;
context->update_pte = ept_update_pte;
context->root_level = PT64_ROOT_4LEVEL;
context->root_hpa = INVALID_PAGE;
context->prev_root = KVM_MMU_ROOT_INFO_INVALID;
context->direct_map = false;
context->base_role.word = root_page_role.word & mmu_base_role_mask.word;
update_permission_bitmask(vcpu, context, true);
Expand Down Expand Up @@ -4819,15 +4805,21 @@ static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu)
update_last_nonleaf_level(vcpu, g_context);
}

static void init_kvm_mmu(struct kvm_vcpu *vcpu)
void kvm_init_mmu(struct kvm_vcpu *vcpu, bool reset_roots)
{
if (reset_roots) {
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
vcpu->arch.mmu.prev_root = KVM_MMU_ROOT_INFO_INVALID;
}

if (mmu_is_nested(vcpu))
init_kvm_nested_mmu(vcpu);
else if (tdp_enabled)
init_kvm_tdp_mmu(vcpu);
else
init_kvm_softmmu(vcpu);
}
EXPORT_SYMBOL_GPL(kvm_init_mmu);

static union kvm_mmu_page_role
kvm_mmu_calc_root_page_role(struct kvm_vcpu *vcpu)
Expand All @@ -4841,7 +4833,7 @@ kvm_mmu_calc_root_page_role(struct kvm_vcpu *vcpu)
void kvm_mmu_reset_context(struct kvm_vcpu *vcpu)
{
kvm_mmu_unload(vcpu);
init_kvm_mmu(vcpu);
kvm_init_mmu(vcpu, true);
}
EXPORT_SYMBOL_GPL(kvm_mmu_reset_context);

Expand Down Expand Up @@ -5245,7 +5237,7 @@ void kvm_mmu_setup(struct kvm_vcpu *vcpu)
{
MMU_WARN_ON(VALID_PAGE(vcpu->arch.mmu.root_hpa));

init_kvm_mmu(vcpu);
kvm_init_mmu(vcpu, true);
}

static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm,
Expand Down
1 change: 1 addition & 0 deletions arch/x86/kvm/mmu.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -61,6 +61,7 @@ void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask, u64 mmio_value);
void
reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context);

void kvm_init_mmu(struct kvm_vcpu *vcpu, bool reset_roots);
void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu);
void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
bool accessed_dirty);
Expand Down

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