From: Michael Roth <michael.roth@xxxxxxx>
In some cases, like with SEV-SNP, guest memory needs to be updated in a
platform-specific manner before it can be safely freed back to the host.
Wire up arch-defined hooks to the .free_folio kvm_gmem_aops callback to
allow for special handling of this sort when freeing memory in response
to FALLOC_FL_PUNCH_HOLE operations and when releasing the inode, and go
ahead and define an arch-specific hook for x86 since it will be needed
for handling memory used for SEV-SNP guests.
Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
Message-Id: <20231230172351.574091-6-michael.roth@xxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/include/asm/kvm-x86-ops.h | 1 +
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/x86.c | 7 +++++++
include/linux/kvm_host.h | 4 ++++
virt/kvm/Kconfig | 4 ++++
virt/kvm/guest_memfd.c | 14 ++++++++++++++
6 files changed, 31 insertions(+)
diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index d26fcad13e36..c81990937ab4 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -140,6 +140,7 @@ KVM_X86_OP_OPTIONAL_RET0(vcpu_get_apicv_inhibit_reasons);
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(gmem_invalidate)
#undef KVM_X86_OP
#undef KVM_X86_OP_OPTIONAL
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 5562a2443c5c..c6c5018376be 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1815,6 +1815,7 @@ 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);
};
struct kvm_x86_nested_ops {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 972524ddcfdb..83b8260443a3 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -13605,6 +13605,13 @@ int kvm_arch_gmem_prepare(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, int max_ord
}
#endif
+#ifdef CONFIG_HAVE_KVM_GMEM_INVALIDATE
+void kvm_arch_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end)
+{
+ static_call_cond(kvm_x86_gmem_invalidate)(start, end);
+}
+#endif
+
int kvm_spec_ctrl_test_value(u64 value)
{
/*
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 1ae65774d9fa..b43b96f876fe 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -2475,4 +2475,8 @@ typedef int (*kvm_gmem_populate_cb)(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn,
long kvm_gmem_populate(struct kvm *kvm, gfn_t gfn, void __user *src, long npages,
kvm_gmem_populate_cb post_populate, void *opaque);
+#ifdef CONFIG_HAVE_KVM_GMEM_INVALIDATE
+void kvm_arch_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end);
+#endif
+
#endif
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index ca870157b2ed..754c6c923427 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -113,3 +113,7 @@ config KVM_GENERIC_PRIVATE_MEM
config HAVE_KVM_GMEM_PREPARE
bool
depends on KVM_PRIVATE_MEM
+
+config HAVE_KVM_GMEM_INVALIDATE
+ bool
+ depends on KVM_PRIVATE_MEM
diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index 5d6c87bb13f6..dfe50c64a552 100644
--- a/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c
@@ -343,10 +343,24 @@ static int kvm_gmem_error_folio(struct address_space *mapping, struct folio *fol
return MF_DELAYED;
}
+#ifdef CONFIG_HAVE_KVM_GMEM_INVALIDATE
+static void kvm_gmem_free_folio(struct folio *folio)
+{
+ struct page *page = folio_page(folio, 0);
+ kvm_pfn_t pfn = page_to_pfn(page);
+ int order = folio_order(folio);
+
+ kvm_arch_gmem_invalidate(pfn, pfn + (1ul << order));
+}
+#endif
+
static const struct address_space_operations kvm_gmem_aops = {
.dirty_folio = noop_dirty_folio,
.migrate_folio = kvm_gmem_migrate_folio,
.error_remove_folio = kvm_gmem_error_folio,
+#ifdef CONFIG_HAVE_KVM_GMEM_INVALIDATE
+ .free_folio = kvm_gmem_free_folio,
+#endif
};
static int kvm_gmem_getattr(struct mnt_idmap *idmap, const struct path *path,
--
2.43.0
