Re: [PATCH v2] x86/hyperv: use helpers to read control registers in hv_snp_boot_ap()

[Yosry Ahmed]

On Mon, Aug 5, 2024 at 1:12 PM Yosry Ahmed <yosryahmed@xxxxxxxxxx> wrote:
>
> Use native_read_cr*() helpers to read control registers into vmsa->cr*
> instead of open-coded assembly.
>
> No functional change intended, unless there was a purpose to specifying
> rax.
>
> Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
> ---
>
> v1 -> v2:
> - Fixed a silly bug that overwrote vmsa->cr3 instead of reading
>   vmsa->cr0.
>
> ---

Friendly ping on this, any thoughts?

>  arch/x86/hyperv/ivm.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
> index b4a851d27c7cb..60fc3ed728304 100644
> --- a/arch/x86/hyperv/ivm.c
> +++ b/arch/x86/hyperv/ivm.c
> @@ -321,9 +321,9 @@ int hv_snp_boot_ap(u32 cpu, unsigned long start_ip)
>
>         vmsa->efer = native_read_msr(MSR_EFER);
>
> -       asm volatile("movq %%cr4, %%rax;" : "=a" (vmsa->cr4));
> -       asm volatile("movq %%cr3, %%rax;" : "=a" (vmsa->cr3));
> -       asm volatile("movq %%cr0, %%rax;" : "=a" (vmsa->cr0));
> +       vmsa->cr4 = native_read_cr4();
> +       vmsa->cr3 = __native_read_cr3();
> +       vmsa->cr0 = native_read_cr0();
>
>         vmsa->xcr0 = 1;
>         vmsa->g_pat = HV_AP_INIT_GPAT_DEFAULT;
> --
> 2.46.0.rc2.264.g509ed76dc8-goog
>