[PATCH RFC v3 40/43] KVM: x86: Add support for applying content modes

[Ackerley Tng <ackerleytng@google.com>]

For x86, override the default implementations of content mode functions to
handle reporting of supported content modes, and application of requested
modes based on x86 VM types.

Signed-off-by: Ackerley Tng <ackerleytng@google.com>
---
 arch/x86/kvm/x86.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9c29407712580..49c19897a9c30 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -14078,6 +14078,75 @@ void kvm_arch_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end)
 	kvm_x86_call(gmem_invalidate)(start, end);
 }
 #endif
+
+u64 kvm_arch_gmem_supported_content_modes(struct kvm *kvm)
+{
+	switch (kvm->arch.vm_type) {
+	case KVM_X86_SW_PROTECTED_VM:
+		return KVM_SET_MEMORY_ATTRIBUTES2_ZERO |
+		       KVM_SET_MEMORY_ATTRIBUTES2_PRESERVE;
+	case KVM_X86_SEV_VM:
+	case KVM_X86_SEV_ES_VM:
+	case KVM_X86_SNP_VM:
+	case KVM_X86_TDX_VM:
+		return 0;
+	case KVM_X86_DEFAULT_VM:
+	default:
+		WARN_ONCE(1, "Unexpected conversion request for vm_type.");
+		return 0;
+	}
+}
+
+int kvm_arch_gmem_apply_content_mode_zero(struct kvm *kvm,
+					  struct folio *folio)
+{
+	switch (kvm->arch.vm_type) {
+	case KVM_X86_SW_PROTECTED_VM:
+		return kvm_gmem_apply_content_mode_zero(folio);
+	default:
+		WARN_ONCE(1, "Unexpected request to zero for vm_type.");
+		return -EOPNOTSUPP;
+	}
+}
+
+int kvm_arch_gmem_apply_content_mode_preserve(struct kvm *kvm,
+					      struct folio *folio)
+{
+	switch (kvm->arch.vm_type) {
+	case KVM_X86_SW_PROTECTED_VM:
+		return 0;
+	default:
+		WARN_ONCE(1, "Unexpected request to preserve for vm_type.");
+		return -EOPNOTSUPP;
+	}
+}
+
+int kvm_arch_gmem_apply_content_mode_unspecified(struct kvm *kvm,
+						 struct folio *folio)
+{
+	switch (kvm->arch.vm_type) {
+	case KVM_X86_SW_PROTECTED_VM: {
+		char *addr;
+		int i;
+
+		/*
+		 * KVM_X86_SW_PROTECTED_VM is a test vehicle, this
+		 * case is just for testing and does not need to be
+		 * performant.
+		 */
+		for (i = 0; i < folio_nr_pages(folio); ++i) {
+			addr = kmap_local_page(folio_page(folio, i));
+			get_random_bytes(addr, PAGE_SIZE);
+			kunmap_local(addr);
+		}
+
+		return 0;
+	}
+	default:
+		return 0;
+	}
+}
+
 #endif
 
 int kvm_spec_ctrl_test_value(u64 value)

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