diff mbox series

[11/12] KVM: MMU: remove kvm_mmu_calc_root_page_role

Message ID 20220209170020.1775368-12-pbonzini@redhat.com (mailing list archive)
State New, archived
Headers show
Series KVM: MMU: do not unload MMU roots on all role changes | expand

Commit Message

Paolo Bonzini Feb. 9, 2022, 5 p.m. UTC 
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.

For the !tdp_enabled case, it would also have been possible to use
the role that is already in vcpu->arch.mmu.

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

Comments

Sean Christopherson Feb. 11, 2022, 5:53 p.m. UTC | #1 
IMO, the shortlog is too literal and doesn't help understand the implications of
the change.  I prefer something like:

  KVM: x86/mmu: Always use current mmu's role when loading new PGD

On Wed, Feb 09, 2022, Paolo Bonzini wrote:
> 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.
> 
> For the !tdp_enabled case, it would also have been possible to use
> the role that is already in vcpu->arch.mmu.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---

With a different shortlog and newline,

Reviewed-by: Sean Christopherson <seanjc@google.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 df9e0a43513c..38b40ddcaad7 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;
> @@ -4172,9 +4170,9 @@ static bool fast_pgd_switch(struct kvm_vcpu *vcpu, gpa_t new_pgd,
>  		return cached_root_find_and_replace(vcpu, 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)
>  {
> +	union kvm_mmu_page_role new_role = vcpu->arch.mmu->mmu_role.base;

Newline needed.

>  	if (!fast_pgd_switch(vcpu, new_pgd, new_role)) {
>  		/* kvm_mmu_ensure_valid_pgd will set up a new root.  */
>  		return;
diff mbox series

Patch

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index df9e0a43513c..38b40ddcaad7 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;
@@ -4172,9 +4170,9 @@  static bool fast_pgd_switch(struct kvm_vcpu *vcpu, gpa_t new_pgd,
 		return cached_root_find_and_replace(vcpu, 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)
 {
+	union kvm_mmu_page_role new_role = vcpu->arch.mmu->mmu_role.base;
 	if (!fast_pgd_switch(vcpu, new_pgd, new_role)) {
 		/* kvm_mmu_ensure_valid_pgd will set up a new root.  */
 		return;
@@ -4209,11 +4207,6 @@  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)
@@ -4883,7 +4876,7 @@  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);
 
@@ -4939,7 +4932,7 @@  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);
 
@@ -5024,20 +5017,6 @@  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)
 {
 	/*