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

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

Posted by Yosry Ahmed 2 months, 3 weeks ago

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@google.com>
---

v1 -> v2:
- Fixed a silly bug that overwrote vmsa->cr3 instead of reading
  vmsa->cr0.

---
 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

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

Posted by Yosry Ahmed 2 months, 2 weeks ago

On Mon, Aug 5, 2024 at 1:12 PM Yosry Ahmed <yosryahmed@google.com> 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@google.com>
> ---
>
> 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
>

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

Posted by Wei Liu 2 months, 1 week ago

On Wed, Aug 14, 2024 at 04:54:32PM -0700, Yosry Ahmed wrote:
> On Mon, Aug 5, 2024 at 1:12 PM Yosry Ahmed <yosryahmed@google.com> 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@google.com>
> > ---
> >
> > v1 -> v2:
> > - Fixed a silly bug that overwrote vmsa->cr3 instead of reading
> >   vmsa->cr0.
> >
> > ---
> 
> Friendly ping on this, any thoughts?

Applied to hyperv-next. Thanks.

> 
> >  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
> >