Re: [PATCH v8 06/46] KVM: Enumerate support for PRIVATE memory iff kvm_arch_has_private_mem is defined
From: Xiaoyao Li <hidden>
Date: 2026-07-01 09:20:27
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On 6/19/2026 8:31 AM, Ackerley Tng via B4 Relay wrote:
From: Ackerley Tng <redacted> Explicitly guard reporting support for KVM_MEMORY_ATTRIBUTE_PRIVATE based on kvm_arch_has_private_mem being #defined in anticipation of decoupling kvm_supported_mem_attributes() from CONFIG_KVM_VM_MEMORY_ATTRIBUTES.
Well, after this series, kvm_supported_mem_attributes() is renamed to kvm_supported_vm_mem_attributes(), and it's still under CONFIG_KVM_VM_MEMORY_ATTRIBUTES.
guest_memfd support for memory attributes will be unconditional to avoid yet more macros (all architectures that support guest_memfd are expected to use per-gmem attributes at some point), at which point enumerating support KVM_MEMORY_ATTRIBUTE_PRIVATE based solely on memory attributes being supported _somewhere_ would result in KVM over-reporting support on arm64.
I don't understand it. This patch only changes the behavior of kvm_supported_mem_attributes(), the usage of which is guarded by CONFIG_KVM_VM_MEMORY_ATTRIBUTES. This is config is only visible to x86 due to patch 03. How does it affect arm64?
quoted hunk ↗ jump to hunk
Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Fuad Tabba <redacted> Signed-off-by: Ackerley Tng <redacted> --- virt/kvm/kvm_main.c | 2 ++ 1 file changed, 2 insertions(+)diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1ccc4895a4c26..7b989b659cf82 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c@@ -2421,8 +2421,10 @@ static int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm, #ifdef CONFIG_KVM_VM_MEMORY_ATTRIBUTES static u64 kvm_supported_mem_attributes(struct kvm *kvm) { +#ifdef kvm_arch_has_private_mem if (!kvm || kvm_arch_has_private_mem(kvm)) return KVM_MEMORY_ATTRIBUTE_PRIVATE; +#endif return 0; }