[PATCH v2 24/25] KVM: x86/mmu: initialize constant-value fields just once

Paolo Bonzini
2022-02-21T16:23:37Z

The get_guest_pgd, get_pdptr and inject_page_fault pointers are constant
for all three of root_mmu, guest_mmu and nested_mmu. In fact, the guest_mmu
function pointers depend on the processor vendor and need to be retrieved
from three new nested_ops, but the others are absolutely the same.

Opportunistically stop initializing get_pdptr for nested EPT, since it does
not have PDPTRs.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/include/asm/kvm_host.h | 5 +++
arch/x86/kvm/mmu/mmu.c | 65 +++++++++++++++++----------------
arch/x86/kvm/svm/nested.c | 9 +++--
arch/x86/kvm/vmx/nested.c | 5 +--
4 files changed, 46 insertions(+), 38 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index af90d0653139..b70965235c31 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1503,6 +1503,11 @@ struct kvm_x86_nested_ops {
uint16_t (*get_evmcs_version)(struct kvm_vcpu *vcpu);
void (*inject_page_fault)(struct kvm_vcpu *vcpu,
struct x86_exception *fault);
+ void (*inject_nested_tdp_vmexit)(struct kvm_vcpu *vcpu,
+ struct x86_exception *fault);
+
+ unsigned long (*get_nested_pgd)(struct kvm_vcpu *vcpu);
+ u64 (*get_nested_pdptr)(struct kvm_vcpu *vcpu, int index);
};

struct kvm_x86_init_ops {
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 8eb2c0373309..27cb6ba5a3b0 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4743,12 +4743,6 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu, union kvm_mmu_paging_mode cp

context->cpu_mode.as_u64 = cpu_mode.as_u64;
context->root_role.word = root_role.word;
- context->page_fault = kvm_tdp_page_fault;
- context->sync_page = nonpaging_sync_page;
- context->invlpg = NULL;
- context->get_guest_pgd = kvm_get_guest_cr3;
- context->get_pdptr = kvm_pdptr_read;
- context->inject_page_fault = kvm_inject_page_fault;

if (!is_cr0_pg(context))
context->gva_to_gpa = nonpaging_gva_to_gpa;
@@ -4758,7 +4752,6 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu, union kvm_mmu_paging_mode cp
context->gva_to_gpa = paging32_gva_to_gpa;

reset_guest_paging_metadata(vcpu, context);
- reset_tdp_shadow_zero_bits_mask(context);
}

static void shadow_mmu_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *context,
@@ -4783,8 +4776,8 @@ static void shadow_mmu_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *conte
reset_shadow_zero_bits_mask(vcpu, context);
}

-static void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu,
- union kvm_mmu_paging_mode cpu_mode)
+static void init_kvm_softmmu(struct kvm_vcpu *vcpu,
+ union kvm_mmu_paging_mode cpu_mode)
{
struct kvm_mmu *context = &vcpu->arch.root_mmu;
union kvm_mmu_page_role root_role;
@@ -4880,18 +4873,6 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
}
EXPORT_SYMBOL_GPL(kvm_init_shadow_ept_mmu);

-static void init_kvm_softmmu(struct kvm_vcpu *vcpu,
- union kvm_mmu_paging_mode cpu_mode)
-{
- struct kvm_mmu *context = &vcpu->arch.root_mmu;
-
- kvm_init_shadow_mmu(vcpu, cpu_mode);
-
- context->get_guest_pgd = kvm_get_guest_cr3;
- context->get_pdptr = kvm_pdptr_read;
- context->inject_page_fault = kvm_inject_page_fault_shadow;
-}
-
static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu, union kvm_mmu_paging_mode new_mode)
{
struct kvm_mmu *g_context = &vcpu->arch.nested_mmu;
@@ -4899,16 +4880,7 @@ static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu, union kvm_mmu_paging_mode
if (new_mode.as_u64 == g_context->cpu_mode.as_u64)
return;

- g_context->cpu_mode.as_u64 = new_mode.as_u64;
- g_context->get_guest_pgd = kvm_get_guest_cr3;
- g_context->get_pdptr = kvm_pdptr_read;
- g_context->inject_page_fault = kvm_inject_page_fault;
-
- /*
- * L2 page tables are never shadowed, so there is no need to sync
- * SPTEs.
- */
- g_context->invlpg = NULL;
+ g_context->cpu_mode.as_u64 = new_mode.as_u64;

/*
* Note that arch.mmu->gva_to_gpa translates l2_gpa to l1_gpa using
@@ -5477,6 +5449,37 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)

vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO;

+ vcpu->arch.root_mmu.get_guest_pgd = kvm_get_guest_cr3;
+ vcpu->arch.root_mmu.get_pdptr = kvm_pdptr_read;
+
+ if (tdp_enabled) {
+ vcpu->arch.root_mmu.inject_page_fault = kvm_inject_page_fault;
+ vcpu->arch.root_mmu.page_fault = kvm_tdp_page_fault;
+ vcpu->arch.root_mmu.sync_page = nonpaging_sync_page;
+ vcpu->arch.root_mmu.invlpg = NULL;
+ reset_tdp_shadow_zero_bits_mask(&vcpu->arch.root_mmu);
+
+ vcpu->arch.guest_mmu.get_guest_pgd = kvm_x86_ops.nested_ops->get_nested_pgd;
+ vcpu->arch.guest_mmu.get_pdptr = kvm_x86_ops.nested_ops->get_nested_pdptr;
+ vcpu->arch.guest_mmu.inject_page_fault = kvm_x86_ops.nested_ops->inject_nested_tdp_vmexit;
+ } else {
+ vcpu->arch.root_mmu.inject_page_fault = kvm_inject_page_fault_shadow;
+ /*
+ * page_fault, sync_page, invlpg are set at runtime depending
+ * on the guest paging mode.
+ */
+ }
+
+ vcpu->arch.nested_mmu.get_guest_pgd = kvm_get_guest_cr3;
+ vcpu->arch.nested_mmu.get_pdptr = kvm_pdptr_read;
+ vcpu->arch.nested_mmu.inject_page_fault = kvm_inject_page_fault;
+
+ /*
+ * L2 page tables are never shadowed, so there is no need to sync
+ * SPTEs.
+ */
+ vcpu->arch.nested_mmu.invlpg = NULL;
+
vcpu->arch.mmu = &vcpu->arch.root_mmu;
vcpu->arch.walk_mmu = &vcpu->arch.root_mmu;

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index ff58c9ebc552..713c7531de99 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -109,10 +109,8 @@ 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);
- 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;
- vcpu->arch.walk_mmu = &vcpu->arch.nested_mmu;
+
+ vcpu->arch.walk_mmu = &vcpu->arch.nested_mmu;
}

static void nested_svm_uninit_mmu_context(struct kvm_vcpu *vcpu)
@@ -1569,4 +1567,7 @@ struct kvm_x86_nested_ops svm_nested_ops = {
.get_state = svm_get_nested_state,
.set_state = svm_set_nested_state,
.inject_page_fault = svm_inject_page_fault_nested,
+ .inject_nested_tdp_vmexit = nested_svm_inject_npf_exit,
+ .get_nested_pgd = nested_svm_get_tdp_cr3,
+ .get_nested_pdptr = nested_svm_get_tdp_pdptr,
};
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 564c60566da7..02df0f4fccef 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -414,9 +414,6 @@ static void nested_ept_init_mmu_context(struct kvm_vcpu *vcpu)

vcpu->arch.mmu = &vcpu->arch.guest_mmu;
nested_ept_new_eptp(vcpu);
- vcpu->arch.mmu->get_guest_pgd = nested_ept_get_eptp;
- vcpu->arch.mmu->inject_page_fault = nested_ept_inject_page_fault;
- vcpu->arch.mmu->get_pdptr = kvm_pdptr_read;

vcpu->arch.walk_mmu = &vcpu->arch.nested_mmu;
}
@@ -6805,4 +6802,6 @@ struct kvm_x86_nested_ops vmx_nested_ops = {
.enable_evmcs = nested_enable_evmcs,
.get_evmcs_version = nested_get_evmcs_version,
.inject_page_fault = vmx_inject_page_fault_nested,
+ .inject_nested_tdp_vmexit = nested_ept_inject_page_fault,
+ .get_nested_pgd = nested_ept_get_eptp,
};
--
2.31.1