2022-11-04 08:04:28

by Jürgen Groß

[permalink] [raw]
Subject: [PATCH v2 3/5] x86: drop 32-bit Xen PV guest code in update_task_stack()

Testing for Xen PV guest mode in a 32-bit only code section can be
dropped, as Xen PV guests are supported in 64-bit mode only.

While at it switch from boot_cpu_has() to cpu_feature_enabled() in the
64-bit part of the code.

Signed-off-by: Juergen Gross <[email protected]>
---
arch/x86/include/asm/switch_to.h | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/switch_to.h b/arch/x86/include/asm/switch_to.h
index c08eb0fdd11f..5c91305d09d2 100644
--- a/arch/x86/include/asm/switch_to.h
+++ b/arch/x86/include/asm/switch_to.h
@@ -66,13 +66,10 @@ static inline void update_task_stack(struct task_struct *task)
{
/* sp0 always points to the entry trampoline stack, which is constant: */
#ifdef CONFIG_X86_32
- if (static_cpu_has(X86_FEATURE_XENPV))
- load_sp0(task->thread.sp0);
- else
- this_cpu_write(cpu_tss_rw.x86_tss.sp1, task->thread.sp0);
+ this_cpu_write(cpu_tss_rw.x86_tss.sp1, task->thread.sp0);
#else
/* Xen PV enters the kernel on the thread stack. */
- if (static_cpu_has(X86_FEATURE_XENPV))
+ if (cpu_feature_enabled(X86_FEATURE_XENPV))
load_sp0(task_top_of_stack(task));
#endif
}
--
2.35.3



2022-11-04 16:19:55

by Dave Hansen

[permalink] [raw]
Subject: Re: [PATCH v2 3/5] x86: drop 32-bit Xen PV guest code in update_task_stack()

On 11/4/22 00:26, Juergen Gross wrote:
> Testing for Xen PV guest mode in a 32-bit only code section can be
> dropped, as Xen PV guests are supported in 64-bit mode only.
>
> While at it switch from boot_cpu_has() to cpu_feature_enabled() in the
> 64-bit part of the code.

Acked-by: Dave Hansen <[email protected]>

Subject: [tip: x86/cpu] x86/cpu: Drop 32-bit Xen PV guest code in update_task_stack()

The following commit has been merged into the x86/cpu branch of tip:

Commit-ID: dfbd9e4059c4edad4d92ef7f3deb4954f76e4ba0
Gitweb: https://git.kernel.org/tip/dfbd9e4059c4edad4d92ef7f3deb4954f76e4ba0
Author: Juergen Gross <[email protected]>
AuthorDate: Fri, 04 Nov 2022 08:26:59 +01:00
Committer: Borislav Petkov <[email protected]>
CommitterDate: Tue, 22 Nov 2022 16:14:15 +01:00

x86/cpu: Drop 32-bit Xen PV guest code in update_task_stack()

Testing for Xen PV guest mode in a 32-bit only code section can be
dropped, as Xen PV guests are supported in 64-bit mode only.

While at it, switch from boot_cpu_has() to cpu_feature_enabled() in the
64-bit part of the code.

Signed-off-by: Juergen Gross <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Acked-by: Dave Hansen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
arch/x86/include/asm/switch_to.h | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/switch_to.h b/arch/x86/include/asm/switch_to.h
index c08eb0f..5c91305 100644
--- a/arch/x86/include/asm/switch_to.h
+++ b/arch/x86/include/asm/switch_to.h
@@ -66,13 +66,10 @@ static inline void update_task_stack(struct task_struct *task)
{
/* sp0 always points to the entry trampoline stack, which is constant: */
#ifdef CONFIG_X86_32
- if (static_cpu_has(X86_FEATURE_XENPV))
- load_sp0(task->thread.sp0);
- else
- this_cpu_write(cpu_tss_rw.x86_tss.sp1, task->thread.sp0);
+ this_cpu_write(cpu_tss_rw.x86_tss.sp1, task->thread.sp0);
#else
/* Xen PV enters the kernel on the thread stack. */
- if (static_cpu_has(X86_FEATURE_XENPV))
+ if (cpu_feature_enabled(X86_FEATURE_XENPV))
load_sp0(task_top_of_stack(task));
#endif
}