Hypervisor leaf 5 is PV-specific, but is gated with !is_hvm_domain(),
which stays a runtime test in a build without PV support. Test for a
PV domain directly so the compiler can discard the leaf when
CONFIG_PV is disabled.

Suggested-by: Roger Pau Monné <roger@xenproject.org>
Signed-off-by: Jiaqing Zhao <Zhao.Jiaqing@amd.com>
---
 xen/arch/x86/cpuid.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/cpuid.c b/xen/arch/x86/cpuid.c
index 6e9b15c9c3..a9aeb2d268 100644
--- a/xen/arch/x86/cpuid.c
+++ b/xen/arch/x86/cpuid.c
@@ -157,7 +157,7 @@ static void cpuid_hypervisor_leaves(const struct vcpu *v, uint32_t leaf,
         break;
 
     case 5: /* PV-specific parameters */
-        if ( is_hvm_domain(d) || subleaf != 0 )
+        if ( !is_pv_domain(d) || subleaf != 0 )
             break;
 
         res->b = flsl(get_upper_mfn_bound()) + PAGE_SHIFT;
-- 
2.53.0

On Wed, Aug 26, 2026 at 03:25:26PM +0800, Jiaqing Zhao wrote:
> Hypervisor leaf 5 is PV-specific, but is gated with !is_hvm_domain(),

I would maybe write "..., but is gated using is_hvm_domain()".

> which stays a runtime test in a build without PV support. Test for a
> PV domain directly so the compiler can discard the leaf when
> CONFIG_PV is disabled.
> 
> Suggested-by: Roger Pau Monné <roger@xenproject.org>
> Signed-off-by: Jiaqing Zhao <Zhao.Jiaqing@amd.com>

Acked-by: Roger Pau Monné <roger@xenproject.org>

Thanks, Roger.

On 26.08.2026 09:25, Jiaqing Zhao wrote:
> Hypervisor leaf 5 is PV-specific, but is gated with !is_hvm_domain(),
> which stays a runtime test in a build without PV support. Test for a
> PV domain directly so the compiler can discard the leaf when
> CONFIG_PV is disabled.
> 
> Suggested-by: Roger Pau Monné <roger@xenproject.org>
> Signed-off-by: Jiaqing Zhao <Zhao.Jiaqing@amd.com>

Reviewed-by: Jan Beulich <jbeulich@suse.com>