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x86/kvm/mmu: check if tdp/shadow MMU reconfiguration is needed
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MMU reconfiguration in init_kvm_tdp_mmu()/kvm_init_shadow_mmu() can be
avoided if the source data used to configure it didn't change; enhance
MMU extended role with the required fields and consolidate common code in
kvm_calc_mmu_role_common().

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@vittyvk @bonzini
vittyvk authored and bonzini committed Oct 16, 2018
1 parent a336282 commit 7dcd575
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Showing 2 changed files with 63 additions and 34 deletions.
2 changes: 2 additions & 0 deletions arch/x86/include/asm/kvm_host.h
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Original file line number Diff line number Diff line change
Expand Up @@ -293,10 +293,12 @@ union kvm_mmu_extended_role {
struct {
unsigned int valid:1;
unsigned int execonly:1;
unsigned int cr0_pg:1;
unsigned int cr4_pse:1;
unsigned int cr4_pke:1;
unsigned int cr4_smap:1;
unsigned int cr4_smep:1;
unsigned int cr4_la57:1;
};
};

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95 changes: 61 additions & 34 deletions arch/x86/kvm/mmu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4728,37 +4728,61 @@ static union kvm_mmu_extended_role kvm_calc_mmu_role_ext(struct kvm_vcpu *vcpu)
{
union kvm_mmu_extended_role ext = {0};

ext.cr0_pg = !!is_paging(vcpu);
ext.cr4_smep = !!kvm_read_cr4_bits(vcpu, X86_CR4_SMEP);
ext.cr4_smap = !!kvm_read_cr4_bits(vcpu, X86_CR4_SMAP);
ext.cr4_pse = !!is_pse(vcpu);
ext.cr4_pke = !!kvm_read_cr4_bits(vcpu, X86_CR4_PKE);
ext.cr4_la57 = !!kvm_read_cr4_bits(vcpu, X86_CR4_LA57);

ext.valid = 1;

return ext;
}

static union kvm_mmu_page_role
kvm_calc_tdp_mmu_root_page_role(struct kvm_vcpu *vcpu)
static union kvm_mmu_role kvm_calc_mmu_role_common(struct kvm_vcpu *vcpu,
bool base_only)
{
union kvm_mmu_role role = {0};

role.base.access = ACC_ALL;
role.base.nxe = !!is_nx(vcpu);
role.base.cr4_pae = !!is_pae(vcpu);
role.base.cr0_wp = is_write_protection(vcpu);
role.base.smm = is_smm(vcpu);
role.base.guest_mode = is_guest_mode(vcpu);

if (base_only)
return role;

role.ext = kvm_calc_mmu_role_ext(vcpu);

return role;
}

static union kvm_mmu_role
kvm_calc_tdp_mmu_root_page_role(struct kvm_vcpu *vcpu, bool base_only)
{
union kvm_mmu_page_role role = {0};
union kvm_mmu_role role = kvm_calc_mmu_role_common(vcpu, base_only);

role.guest_mode = is_guest_mode(vcpu);
role.smm = is_smm(vcpu);
role.ad_disabled = (shadow_accessed_mask == 0);
role.level = kvm_x86_ops->get_tdp_level(vcpu);
role.direct = true;
role.access = ACC_ALL;
role.base.ad_disabled = (shadow_accessed_mask == 0);
role.base.level = kvm_x86_ops->get_tdp_level(vcpu);
role.base.direct = true;

return role;
}

static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
{
struct kvm_mmu *context = vcpu->arch.mmu;
union kvm_mmu_role new_role =
kvm_calc_tdp_mmu_root_page_role(vcpu, false);

context->mmu_role.base.word = mmu_base_role_mask.word &
kvm_calc_tdp_mmu_root_page_role(vcpu).word;
new_role.base.word &= mmu_base_role_mask.word;
if (new_role.as_u64 == context->mmu_role.as_u64)
return;

context->mmu_role.as_u64 = new_role.as_u64;
context->page_fault = tdp_page_fault;
context->sync_page = nonpaging_sync_page;
context->invlpg = nonpaging_invlpg;
Expand Down Expand Up @@ -4798,36 +4822,36 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
reset_tdp_shadow_zero_bits_mask(vcpu, context);
}

static union kvm_mmu_page_role
kvm_calc_shadow_mmu_root_page_role(struct kvm_vcpu *vcpu)
{
union kvm_mmu_page_role role = {0};
bool smep = kvm_read_cr4_bits(vcpu, X86_CR4_SMEP);
bool smap = kvm_read_cr4_bits(vcpu, X86_CR4_SMAP);

role.nxe = is_nx(vcpu);
role.cr4_pae = !!is_pae(vcpu);
role.cr0_wp = is_write_protection(vcpu);
role.smep_andnot_wp = smep && !is_write_protection(vcpu);
role.smap_andnot_wp = smap && !is_write_protection(vcpu);
role.guest_mode = is_guest_mode(vcpu);
role.smm = is_smm(vcpu);
role.direct = !is_paging(vcpu);
role.access = ACC_ALL;
static union kvm_mmu_role
kvm_calc_shadow_mmu_root_page_role(struct kvm_vcpu *vcpu, bool base_only)
{
union kvm_mmu_role role = kvm_calc_mmu_role_common(vcpu, base_only);

role.base.smep_andnot_wp = role.ext.cr4_smep &&
!is_write_protection(vcpu);
role.base.smap_andnot_wp = role.ext.cr4_smap &&
!is_write_protection(vcpu);
role.base.direct = !is_paging(vcpu);

if (!is_long_mode(vcpu))
role.level = PT32E_ROOT_LEVEL;
role.base.level = PT32E_ROOT_LEVEL;
else if (is_la57_mode(vcpu))
role.level = PT64_ROOT_5LEVEL;
role.base.level = PT64_ROOT_5LEVEL;
else
role.level = PT64_ROOT_4LEVEL;
role.base.level = PT64_ROOT_4LEVEL;

return role;
}

void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu)
{
struct kvm_mmu *context = vcpu->arch.mmu;
union kvm_mmu_role new_role =
kvm_calc_shadow_mmu_root_page_role(vcpu, false);

new_role.base.word &= mmu_base_role_mask.word;
if (new_role.as_u64 == context->mmu_role.as_u64)
return;

if (!is_paging(vcpu))
nonpaging_init_context(vcpu, context);
Expand All @@ -4838,8 +4862,7 @@ void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu)
else
paging32_init_context(vcpu, context);

context->mmu_role.base.word = mmu_base_role_mask.word &
kvm_calc_shadow_mmu_root_page_role(vcpu).word;
context->mmu_role.as_u64 = new_role.as_u64;
reset_shadow_zero_bits_mask(vcpu, context);
}
EXPORT_SYMBOL_GPL(kvm_init_shadow_mmu);
Expand Down Expand Up @@ -4977,10 +5000,14 @@ EXPORT_SYMBOL_GPL(kvm_init_mmu);
static union kvm_mmu_page_role
kvm_mmu_calc_root_page_role(struct kvm_vcpu *vcpu)
{
union kvm_mmu_role role;

if (tdp_enabled)
return kvm_calc_tdp_mmu_root_page_role(vcpu);
role = kvm_calc_tdp_mmu_root_page_role(vcpu, true);
else
return kvm_calc_shadow_mmu_root_page_role(vcpu);
role = kvm_calc_shadow_mmu_root_page_role(vcpu, true);

return role.base;
}

void kvm_mmu_reset_context(struct kvm_vcpu *vcpu)
Expand Down

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