Messages in this thread Patch in this message | | | From | Xin Li <> | Subject | [RFC PATCH 23/32] x86/fred: update MSR_IA32_FRED_RSP0 during task switch | Date | Mon, 19 Dec 2022 22:36:49 -0800 |
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From: "H. Peter Anvin (Intel)" <hpa@zytor.com>
MSR_IA32_FRED_RSP0 is used during ring 3 event delivery, and needs to be updated to point to the top of next task stack during task switch.
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com> Signed-off-by: Xin Li <xin3.li@intel.com> --- arch/x86/include/asm/switch_to.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/switch_to.h b/arch/x86/include/asm/switch_to.h index c08eb0fdd11f..c28170d4fbba 100644 --- a/arch/x86/include/asm/switch_to.h +++ b/arch/x86/include/asm/switch_to.h @@ -71,9 +71,13 @@ static inline void update_task_stack(struct task_struct *task) else 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_FRED)) { + wrmsrl(MSR_IA32_FRED_RSP0, + task_top_of_stack(task) + TOP_OF_KERNEL_STACK_PADDING); + } else if (static_cpu_has(X86_FEATURE_XENPV)) { + /* Xen PV enters the kernel on the thread stack. */ load_sp0(task_top_of_stack(task)); + } #endif } -- 2.34.1
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