From 9249bcdea0c6db4f450a9267aa6da5b4dd4153ca Mon Sep 17 00:00:00 2001 From: John Allen Date: Wed, 24 Sep 2025 20:08:51 +0000 Subject: x86/boot: Move boot_*msr helpers to asm/shared/msr.h The boot_{rdmsr,wrmsr}() helpers are *just* the barebones MSR access functionality, without any tracing or exception handling glue as it is done in kernel proper. Move these helpers to asm/shared/msr.h and rename to raw_{rdmsr,wrmsr}() to indicate what they are. [ bp: Correct the reason why those helpers exist. I should've caught that in the original patch that added them: 176db622573f ("x86/boot: Introduce helpers for MSR reads/writes" but oh well... - fixup include path delimiters to <> ] Signed-off-by: John Allen Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Link: https://patch.msgid.link/all/20250924200852.4452-2-john.allen@amd.com --- arch/x86/include/asm/shared/msr.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'arch/x86/include') diff --git a/arch/x86/include/asm/shared/msr.h b/arch/x86/include/asm/shared/msr.h index 1e6ec10b3a15..a20b1c08c99f 100644 --- a/arch/x86/include/asm/shared/msr.h +++ b/arch/x86/include/asm/shared/msr.h @@ -12,4 +12,19 @@ struct msr { }; }; +/* + * The kernel proper already defines rdmsr()/wrmsr(), but they are not for the + * boot kernel since they rely on tracepoint/exception handling infrastructure + * that's not available here. + */ +static inline void raw_rdmsr(unsigned int reg, struct msr *m) +{ + asm volatile("rdmsr" : "=a" (m->l), "=d" (m->h) : "c" (reg)); +} + +static inline void raw_wrmsr(unsigned int reg, const struct msr *m) +{ + asm volatile("wrmsr" : : "c" (reg), "a"(m->l), "d" (m->h) : "memory"); +} + #endif /* _ASM_X86_SHARED_MSR_H */ -- cgit v1.2.3