Re: [PATCH 4/4] i386/cpu: Update how the EBX register of CPUID 0x8000001F is set

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Tom Lendacky (thomas.lendacky@amd.com) wrote:
> Update the setting of CPUID 0x8000001F EBX to clearly document the ranges
> associated with fields being set.
> 
> Fixes: 6cb8f2a663 ("cpu/i386: populate CPUID 0x8000_001F when SEV is active")
> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  target/i386/cpu.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 1db1278a59..d4b806cfec 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -5853,8 +5853,8 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
>          if (sev_enabled()) {
>              *eax = 0x2;
>              *eax |= sev_es_enabled() ? 0x8 : 0;
> -            *ebx = sev_get_cbit_position();
> -            *ebx |= sev_get_reduced_phys_bits() << 6;
> +            *ebx = sev_get_cbit_position() & 0x3f; /* EBX[5:0] */
> +            *ebx |= (sev_get_reduced_phys_bits() & 0x3f) << 6; /* EBX[11:6] */
>          }
>          break;
>      default:
> -- 
> 2.37.3
> 
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK