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x86/fred: Update MSR_IA32_FRED_RSP0 during task switch

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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>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Shan Kang <shan.kang@intel.com>
Link: https://lore.kernel.org/r/20231205105030.8698-18-xin3.li@intel.com
This commit is contained in:
H. Peter Anvin (Intel) 2023-12-05 02:50:06 -08:00 committed by Borislav Petkov (AMD)
parent 65c9cc9e2c
commit 9356c4b888
1 changed files with 6 additions and 2 deletions
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8
arch/x86/include/asm/switch_to.h
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@ -70,9 +70,13 @@ static inline void update_task_stack(struct task_struct *task)
#ifdef CONFIG_X86_32
this_cpu_write(cpu_tss_rw.x86_tss.sp1, task->thread.sp0);
#else
/* Xen PV enters the kernel on the thread stack. */
if (cpu_feature_enabled(X86_FEATURE_XENPV))
if (cpu_feature_enabled(X86_FEATURE_FRED)) {
/* WRMSRNS is a baseline feature for FRED. */
wrmsrns(MSR_IA32_FRED_RSP0, (unsigned long)task_stack_page(task) + THREAD_SIZE);
} else if (cpu_feature_enabled(X86_FEATURE_XENPV)) {
/* Xen PV enters the kernel on the thread stack. */
load_sp0(task_top_of_stack(task));
}
#endif
}