Re: [RFC PATCH v2 22/25] KVM: x86/mmu: Refactor kvm_mmu_invlpg() to allow skipping the gva flush

[Sean Christopherson <seanjc@google.com>]

On Tue, Jun 16, 2026, Yosry Ahmed wrote:
> Refactor helpers out of kvm_mmu_invalidate_addr() and kvm_mmu_invlpg()
> that take in an extra argument to skip the GVA flush.
> 
> This will be used when invalidating GVAs in a different context than the
> correct one (i.e.  invalidating an L2 GVA from L1), so flushing the
> current context would flush the wrong TLB entries.
> 
> No functional change intended.
> 
> Signed-off-by: Yosry Ahmed <yosry@kernel.org>
> ---
>  arch/x86/kvm/mmu/mmu.c | 23 +++++++++++++++++------
>  1 file changed, 17 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 65c35ed8f4a01..3feb75732f7b4 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -6615,15 +6615,15 @@ static void kvm_mmu_invalidate_addr_in_root(struct kvm_vcpu *vcpu,
>  	write_unlock(&vcpu->kvm->mmu_lock);
>  }
>  
> -void kvm_mmu_invalidate_addr(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> -			     u64 addr, unsigned long roots)
> +static void __kvm_mmu_invalidate_addr(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> +				      u64 addr, unsigned long roots, bool flush_gva)
>  {
>  	int i;
>  
>  	WARN_ON_ONCE(roots & ~KVM_MMU_ROOTS_ALL);
>  
>  	/* It's actually a GPA for vcpu->arch.guest_mmu.  */
> -	if (mmu != &vcpu->arch.guest_mmu) {
> +	if (flush_gva && mmu != &vcpu->arch.guest_mmu) {
>  		/* INVLPG on a non-canonical address is a NOP according to the SDM.  */
>  		if (is_noncanonical_invlpg_address(addr, vcpu))
>  			return;
> @@ -6642,9 +6642,15 @@ void kvm_mmu_invalidate_addr(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
>  			kvm_mmu_invalidate_addr_in_root(vcpu, mmu, addr, mmu->prev_roots[i].hpa);
>  	}
>  }
> +
> +void kvm_mmu_invalidate_addr(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> +			       u64 addr, unsigned long roots)

Rather than kvm_mmu_invalidate_addr() for the wrapper, what if we call this
kvm_mmu_invalidate_gva()?  And then kvm_mmu_invlpg_gva().  Then we don't need
to have the "in_root" version to a quad-underscores helper, and IMO it's more
obvious what's different between the one-line wrappers and the inner helpers.

> +{
> +	__kvm_mmu_invalidate_addr(vcpu, mmu, addr, roots, true);
> +}

Make these one-liners static inlines to avoid the export, and because they're
trivial wrappers that should be inlined.

>  EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_mmu_invalidate_addr);
>  
> -void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva)
> +static void __kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva, bool flush_gva)
>  {
>  	/*
>  	 * INVLPG is required to invalidate any global mappings for the VA,
> @@ -6656,11 +6662,16 @@ void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva)
>  	 * be synced when switching to that new cr3, so nothing needs to be
>  	 * done here for them.
>  	 */
> -	kvm_mmu_invalidate_addr(vcpu, vcpu->arch.walk_mmu, gva, KVM_MMU_ROOTS_ALL);
> +	__kvm_mmu_invalidate_addr(vcpu, vcpu->arch.walk_mmu, gva,
> +				  KVM_MMU_ROOTS_ALL, flush_gva);
>  	++vcpu->stat.invlpg;
>  }
> -EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_mmu_invlpg);
>  
> +void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva)
> +{
> +	__kvm_mmu_invlpg(vcpu, gva, true);
> +}
> +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_mmu_invlpg);
>  
>  void kvm_mmu_invpcid_gva(struct kvm_vcpu *vcpu, gva_t gva, unsigned long pcid)
>  {
> -- 
> 2.54.0.1136.gdb2ca164c4-goog
>