[PATCH v2 11/18] KVM: x86/mmu: Always use current mmu's role when loading new PGD

Paolo Bonzini
2022-02-17T21:04:35Z

Since the guest PGD is now loaded after the MMU has been set up
completely, the desired role for a cache hit is simply the current
mmu_role. There is no need to compute it again, so __kvm_mmu_new_pgd
can be folded in kvm_mmu_new_pgd.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/mmu/mmu.c | 29 ++++-------------------------
1 file changed, 4 insertions(+), 25 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 906a9244ad28..b01160716c6a 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -190,8 +190,6 @@ struct kmem_cache *mmu_page_header_cache;
static struct percpu_counter kvm_total_used_mmu_pages;

static void mmu_spte_set(u64 *sptep, u64 spte);
-static union kvm_mmu_page_role
-kvm_mmu_calc_root_page_role(struct kvm_vcpu *vcpu);

struct kvm_mmu_role_regs {
const unsigned long cr0;
@@ -4191,10 +4189,10 @@ static bool fast_pgd_switch(struct kvm *kvm, struct kvm_mmu *mmu,
return cached_root_find_without_current(kvm, mmu, new_pgd, new_role);
}

-static void __kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd,
- union kvm_mmu_page_role new_role)
+void kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd)
{
struct kvm_mmu *mmu = vcpu->arch.mmu;
+ union kvm_mmu_page_role new_role = mmu->mmu_role.base;

if (!fast_pgd_switch(vcpu->kvm, mmu, new_pgd, new_role)) {
/* kvm_mmu_ensure_valid_pgd will set up a new root. */
@@ -4230,11 +4228,6 @@ static void __kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd,
__clear_sp_write_flooding_count(
to_shadow_page(vcpu->arch.mmu->root.hpa));
}
-
-void kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd)
-{
- __kvm_mmu_new_pgd(vcpu, new_pgd, kvm_mmu_calc_root_page_role(vcpu));
-}
EXPORT_SYMBOL_GPL(kvm_mmu_new_pgd);

static unsigned long get_cr3(struct kvm_vcpu *vcpu)
@@ -4904,7 +4897,7 @@ void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0,
new_role = kvm_calc_shadow_npt_root_page_role(vcpu, &regs);

shadow_mmu_init_context(vcpu, context, &regs, new_role);
- __kvm_mmu_new_pgd(vcpu, nested_cr3, new_role.base);
+ kvm_mmu_new_pgd(vcpu, nested_cr3);
}
EXPORT_SYMBOL_GPL(kvm_init_shadow_npt_mmu);

@@ -4960,7 +4953,7 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
reset_ept_shadow_zero_bits_mask(context, execonly);
}

- __kvm_mmu_new_pgd(vcpu, new_eptp, new_role.base);
+ kvm_mmu_new_pgd(vcpu, new_eptp);
}
EXPORT_SYMBOL_GPL(kvm_init_shadow_ept_mmu);

@@ -5045,20 +5038,6 @@ void kvm_init_mmu(struct kvm_vcpu *vcpu)
}
EXPORT_SYMBOL_GPL(kvm_init_mmu);

-static union kvm_mmu_page_role
-kvm_mmu_calc_root_page_role(struct kvm_vcpu *vcpu)
-{
- struct kvm_mmu_role_regs regs = vcpu_to_role_regs(vcpu);
- union kvm_mmu_role role;
-
- if (tdp_enabled)
- role = kvm_calc_tdp_mmu_root_page_role(vcpu, &regs, true);
- else
- role = kvm_calc_shadow_mmu_root_page_role(vcpu, &regs, true);
-
- return role.base;
-}
-
void kvm_mmu_after_set_cpuid(struct kvm_vcpu *vcpu)
{
/*
--
2.31.1