The exact set of available memory attributes can vary by VM.  In the
future it might vary depending on enabled capabilities, too.  Query the
extension on the VM level instead of on the KVM level, and only after
architecture-specific initialization.

Inspired by an analogous patch by Tom Dohrmann.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 accel/kvm/kvm-all.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 4287e254df8..482c5b24cf6 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -2604,12 +2604,6 @@ static int kvm_init(MachineState *ms)
         goto err;
     }
 
-    kvm_supported_memory_attributes = kvm_check_extension(s, KVM_CAP_MEMORY_ATTRIBUTES);
-    kvm_guest_memfd_supported =
-        kvm_check_extension(s, KVM_CAP_GUEST_MEMFD) &&
-        kvm_check_extension(s, KVM_CAP_USER_MEMORY2) &&
-        (kvm_supported_memory_attributes & KVM_MEMORY_ATTRIBUTE_PRIVATE);
-
     kvm_immediate_exit = kvm_check_extension(s, KVM_CAP_IMMEDIATE_EXIT);
     s->nr_slots_max = kvm_check_extension(s, KVM_CAP_NR_MEMSLOTS);
 
@@ -2723,6 +2717,12 @@ static int kvm_init(MachineState *ms)
         goto err;
     }
 
+    kvm_supported_memory_attributes = kvm_vm_check_extension(s, KVM_CAP_MEMORY_ATTRIBUTES);
+    kvm_guest_memfd_supported =
+        kvm_check_extension(s, KVM_CAP_GUEST_MEMFD) &&
+        kvm_check_extension(s, KVM_CAP_USER_MEMORY2) &&
+        (kvm_supported_memory_attributes & KVM_MEMORY_ATTRIBUTE_PRIVATE);
+
     if (s->kernel_irqchip_split == ON_OFF_AUTO_AUTO) {
         s->kernel_irqchip_split = mc->default_kernel_irqchip_split ? ON_OFF_AUTO_ON : ON_OFF_AUTO_OFF;
     }
-- 
2.46.2

On 10/11/2024 10:59 AM, Paolo Bonzini wrote:
> The exact set of available memory attributes can vary by VM.  In the
> future it might vary depending on enabled capabilities, too.  Query the
> extension on the VM level instead of on the KVM level, and only after
> architecture-specific initialization.
> 
> Inspired by an analogous patch by Tom Dohrmann.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>

> ---
>   accel/kvm/kvm-all.c | 12 ++++++------
>   1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> index 4287e254df8..482c5b24cf6 100644
> --- a/accel/kvm/kvm-all.c
> +++ b/accel/kvm/kvm-all.c
> @@ -2604,12 +2604,6 @@ static int kvm_init(MachineState *ms)
>           goto err;
>       }
>   
> -    kvm_supported_memory_attributes = kvm_check_extension(s, KVM_CAP_MEMORY_ATTRIBUTES);
> -    kvm_guest_memfd_supported =
> -        kvm_check_extension(s, KVM_CAP_GUEST_MEMFD) &&
> -        kvm_check_extension(s, KVM_CAP_USER_MEMORY2) &&
> -        (kvm_supported_memory_attributes & KVM_MEMORY_ATTRIBUTE_PRIVATE);
> -
>       kvm_immediate_exit = kvm_check_extension(s, KVM_CAP_IMMEDIATE_EXIT);
>       s->nr_slots_max = kvm_check_extension(s, KVM_CAP_NR_MEMSLOTS);
>   
> @@ -2723,6 +2717,12 @@ static int kvm_init(MachineState *ms)
>           goto err;
>       }
>   
> +    kvm_supported_memory_attributes = kvm_vm_check_extension(s, KVM_CAP_MEMORY_ATTRIBUTES);
> +    kvm_guest_memfd_supported =
> +        kvm_check_extension(s, KVM_CAP_GUEST_MEMFD) &&
> +        kvm_check_extension(s, KVM_CAP_USER_MEMORY2) &&
> +        (kvm_supported_memory_attributes & KVM_MEMORY_ATTRIBUTE_PRIVATE);
> +
>       if (s->kernel_irqchip_split == ON_OFF_AUTO_AUTO) {
>           s->kernel_irqchip_split = mc->default_kernel_irqchip_split ? ON_OFF_AUTO_ON : ON_OFF_AUTO_OFF;
>       }