From: John Allen Date: Wed, 24 Sep 2025 20:08:51 +0000 (+0000) Subject: x86/boot: Move boot_*msr helpers to asm/shared/msr.h X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=9249bcdea0c6db4f450a9267aa6da5b4dd4153ca;p=thirdparty%2Flinux.git 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 --- diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c index 6e5c32a53d034..c8c1464b3a56e 100644 --- a/arch/x86/boot/compressed/sev.c +++ b/arch/x86/boot/compressed/sev.c @@ -14,6 +14,7 @@ #include #include +#include #include #include #include @@ -397,7 +398,7 @@ void sev_enable(struct boot_params *bp) } /* Set the SME mask if this is an SEV guest. */ - boot_rdmsr(MSR_AMD64_SEV, &m); + raw_rdmsr(MSR_AMD64_SEV, &m); sev_status = m.q; if (!(sev_status & MSR_AMD64_SEV_ENABLED)) return; @@ -446,7 +447,7 @@ u64 sev_get_status(void) if (sev_check_cpu_support() < 0) return 0; - boot_rdmsr(MSR_AMD64_SEV, &m); + raw_rdmsr(MSR_AMD64_SEV, &m); return m.q; } @@ -496,7 +497,7 @@ bool early_is_sevsnp_guest(void) struct msr m; /* Obtain the address of the calling area to use */ - boot_rdmsr(MSR_SVSM_CAA, &m); + raw_rdmsr(MSR_SVSM_CAA, &m); boot_svsm_caa_pa = m.q; /* diff --git a/arch/x86/boot/compressed/sev.h b/arch/x86/boot/compressed/sev.h index 92f79c21939cc..22637b416b46f 100644 --- a/arch/x86/boot/compressed/sev.h +++ b/arch/x86/boot/compressed/sev.h @@ -10,7 +10,7 @@ #ifdef CONFIG_AMD_MEM_ENCRYPT -#include "../msr.h" +#include void snp_accept_memory(phys_addr_t start, phys_addr_t end); u64 sev_get_status(void); @@ -20,7 +20,7 @@ static inline u64 sev_es_rd_ghcb_msr(void) { struct msr m; - boot_rdmsr(MSR_AMD64_SEV_ES_GHCB, &m); + raw_rdmsr(MSR_AMD64_SEV_ES_GHCB, &m); return m.q; } @@ -30,7 +30,7 @@ static inline void sev_es_wr_ghcb_msr(u64 val) struct msr m; m.q = val; - boot_wrmsr(MSR_AMD64_SEV_ES_GHCB, &m); + raw_wrmsr(MSR_AMD64_SEV_ES_GHCB, &m); } #else diff --git a/arch/x86/boot/cpucheck.c b/arch/x86/boot/cpucheck.c index f82de8de5dc62..2e1bb936cba2e 100644 --- a/arch/x86/boot/cpucheck.c +++ b/arch/x86/boot/cpucheck.c @@ -26,9 +26,9 @@ #include #include #include +#include #include "string.h" -#include "msr.h" static u32 err_flags[NCAPINTS]; @@ -134,9 +134,9 @@ int check_cpu(int *cpu_level_ptr, int *req_level_ptr, u32 **err_flags_ptr) struct msr m; - boot_rdmsr(MSR_K7_HWCR, &m); + raw_rdmsr(MSR_K7_HWCR, &m); m.l &= ~(1 << 15); - boot_wrmsr(MSR_K7_HWCR, &m); + raw_wrmsr(MSR_K7_HWCR, &m); get_cpuflags(); /* Make sure it really did something */ err = check_cpuflags(); @@ -148,9 +148,9 @@ int check_cpu(int *cpu_level_ptr, int *req_level_ptr, u32 **err_flags_ptr) struct msr m; - boot_rdmsr(MSR_VIA_FCR, &m); + raw_rdmsr(MSR_VIA_FCR, &m); m.l |= (1 << 1) | (1 << 7); - boot_wrmsr(MSR_VIA_FCR, &m); + raw_wrmsr(MSR_VIA_FCR, &m); set_bit(X86_FEATURE_CX8, cpu.flags); err = check_cpuflags(); @@ -160,14 +160,14 @@ int check_cpu(int *cpu_level_ptr, int *req_level_ptr, u32 **err_flags_ptr) struct msr m, m_tmp; u32 level = 1; - boot_rdmsr(0x80860004, &m); + raw_rdmsr(0x80860004, &m); m_tmp = m; m_tmp.l = ~0; - boot_wrmsr(0x80860004, &m_tmp); + raw_wrmsr(0x80860004, &m_tmp); asm("cpuid" : "+a" (level), "=d" (cpu.flags[0]) : : "ecx", "ebx"); - boot_wrmsr(0x80860004, &m); + raw_wrmsr(0x80860004, &m); err = check_cpuflags(); } else if (err == 0x01 && diff --git a/arch/x86/boot/msr.h b/arch/x86/boot/msr.h deleted file mode 100644 index aed66f7ae199f..0000000000000 --- a/arch/x86/boot/msr.h +++ /dev/null @@ -1,26 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0-only */ -/* - * Helpers/definitions related to MSR access. - */ - -#ifndef BOOT_MSR_H -#define BOOT_MSR_H - -#include - -/* - * 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 boot_rdmsr(unsigned int reg, struct msr *m) -{ - asm volatile("rdmsr" : "=a" (m->l), "=d" (m->h) : "c" (reg)); -} - -static inline void boot_wrmsr(unsigned int reg, const struct msr *m) -{ - asm volatile("wrmsr" : : "c" (reg), "a"(m->l), "d" (m->h) : "memory"); -} - -#endif /* BOOT_MSR_H */ diff --git a/arch/x86/include/asm/shared/msr.h b/arch/x86/include/asm/shared/msr.h index 1e6ec10b3a151..a20b1c08c99fd 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 */