Re: [PATCH v3 04/12] KVM: Rename .gmem_invalidate() to .gmem_reclaim_memory()

[Michael Roth]

On Tue, Jun 30, 2026 at 03:25:59PM -0700, Sean Christopherson wrote:
> Rename .gmem_invalidate() to .gmem_reclaim_memory() as the hook is called
> when a folio is freed, which is far too late and lacks sufficient
> information for KVM to actually invalidate its usage of the memory.
> 
> Keep guest_memfd's trampoline, even though it would be trivial to wire up
> .free_folio() directly to an arch callback, to avoid bleeding guest_memfd
> internals into arch code (specifically, avoid referencing folios in arch
> code).
> 
> Opportunistically guard kvm_x86_ops.gmem_reclaim_memory() with an ifdef to
> ensure the callback will actually be called, e.g. so that non-SEV code
> doesn't try to wire up a callback without enabling
> CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE.
> 
> No functional change intended.
> 
> Cc: Ackerley Tng <ackerleytng@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # 6.12.x
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>

Reviewed-by: Michael Roth <michael.roth@xxxxxxx>

> ---
>  arch/x86/include/asm/kvm-x86-ops.h | 4 +++-
>  arch/x86/include/asm/kvm_host.h    | 4 +++-
>  arch/x86/kvm/svm/sev.c             | 2 +-
>  arch/x86/kvm/svm/svm.c             | 4 +++-
>  arch/x86/kvm/svm/svm.h             | 3 +--
>  arch/x86/kvm/x86.c                 | 4 ++--
>  include/linux/kvm_host.h           | 2 +-
>  virt/kvm/guest_memfd.c             | 2 +-
>  8 files changed, 15 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
> index 83dc5086138b..acae9f6d6c5e 100644
> --- a/arch/x86/include/asm/kvm-x86-ops.h
> +++ b/arch/x86/include/asm/kvm-x86-ops.h
> @@ -147,7 +147,9 @@ KVM_X86_OP_OPTIONAL(get_untagged_addr)
>  KVM_X86_OP_OPTIONAL(alloc_apic_backing_page)
>  KVM_X86_OP_OPTIONAL_RET0(gmem_prepare)
>  KVM_X86_OP_OPTIONAL_RET0(gmem_max_mapping_level)
> -KVM_X86_OP_OPTIONAL(gmem_invalidate)
> +#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE
> +KVM_X86_OP_OPTIONAL(gmem_reclaim_memory)
> +#endif
>  #endif
>  
>  #undef KVM_X86_OP
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index b517257a6315..5e8603deb252 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1901,7 +1901,9 @@ struct kvm_x86_ops {
>  	gva_t (*get_untagged_addr)(struct kvm_vcpu *vcpu, gva_t gva, unsigned int flags);
>  	void *(*alloc_apic_backing_page)(struct kvm_vcpu *vcpu);
>  	int (*gmem_prepare)(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order);
> -	void (*gmem_invalidate)(kvm_pfn_t start, kvm_pfn_t end);
> +#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE
> +	void (*gmem_reclaim_memory)(kvm_pfn_t start, kvm_pfn_t end);
> +#endif
>  	int (*gmem_max_mapping_level)(struct kvm *kvm, kvm_pfn_t pfn, bool is_private);
>  };
>  
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 30792adcfc8e..4465e75494f2 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -5136,7 +5136,7 @@ int sev_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order)
>  	return 0;
>  }
>  
> -void sev_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end)
> +void sev_gmem_reclaim_memory(kvm_pfn_t start, kvm_pfn_t end)
>  {
>  	kvm_pfn_t pfn;
>  
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index ef69a51ab27f..6be0000ab386 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -5460,9 +5460,11 @@ struct kvm_x86_ops svm_x86_ops __initdata = {
>  	.vcpu_get_apicv_inhibit_reasons = avic_vcpu_get_apicv_inhibit_reasons,
>  	.alloc_apic_backing_page = svm_alloc_apic_backing_page,
>  
> +#ifdef CONFIG_KVM_AMD_SEV
>  	.gmem_prepare = sev_gmem_prepare,
> -	.gmem_invalidate = sev_gmem_invalidate,
> +	.gmem_reclaim_memory = sev_gmem_reclaim_memory,
>  	.gmem_max_mapping_level = sev_gmem_max_mapping_level,
> +#endif
>  };
>  
>  /*
> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index d077783c287e..cf7c1a437f38 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -1009,7 +1009,7 @@ int sev_dev_get_attr(u32 group, u64 attr, u64 *val);
>  extern unsigned int max_sev_asid;
>  void sev_handle_rmp_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code);
>  int sev_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order);
> -void sev_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end);
> +void sev_gmem_reclaim_memory(kvm_pfn_t start, kvm_pfn_t end);
>  int sev_gmem_max_mapping_level(struct kvm *kvm, kvm_pfn_t pfn, bool is_private);
>  struct vmcb_save_area *sev_decrypt_vmsa(struct kvm_vcpu *vcpu);
>  void sev_free_decrypted_vmsa(struct kvm_vcpu *vcpu, struct vmcb_save_area *vmsa);
> @@ -1039,7 +1039,6 @@ static inline int sev_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, in
>  {
>  	return 0;
>  }
> -static inline void sev_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end) {}
>  static inline int sev_gmem_max_mapping_level(struct kvm *kvm, kvm_pfn_t pfn, bool is_private)
>  {
>  	return 0;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 0626e835e9eb..6b9a1b0b1460 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -10592,9 +10592,9 @@ int kvm_arch_gmem_prepare(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, int max_ord
>  #endif
>  
>  #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE
> -void kvm_arch_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end)
> +void kvm_arch_gmem_reclaim_memory(kvm_pfn_t start, kvm_pfn_t end)
>  {
> -	kvm_x86_call(gmem_invalidate)(start, end);
> +	kvm_x86_call(gmem_reclaim_memory)(start, end);
>  }
>  #endif
>  #endif
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index ab8cfaec82d3..d777eaadbcd2 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -2607,7 +2607,7 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src,
>  #endif
>  
>  #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE
> -void kvm_arch_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end);
> +void kvm_arch_gmem_reclaim_memory(kvm_pfn_t start, kvm_pfn_t end);
>  #endif
>  
>  #ifdef CONFIG_KVM_GENERIC_PRE_FAULT_MEMORY
> diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
> index 86690683b2fe..db0fcc38b145 100644
> --- a/virt/kvm/guest_memfd.c
> +++ b/virt/kvm/guest_memfd.c
> @@ -530,7 +530,7 @@ static void kvm_gmem_free_folio(struct folio *folio)
>  	kvm_pfn_t pfn = page_to_pfn(page);
>  	int order = folio_order(folio);
>  
> -	kvm_arch_gmem_invalidate(pfn, pfn + (1ul << order));
> +	kvm_arch_gmem_reclaim_memory(pfn, pfn + (1ul << order));
>  }
>  #endif
>  
> -- 
> 2.55.0.rc0.799.gd6f94ed593-goog
>