mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-09-04 20:19:47 +08:00
176db62257
The current set of helpers used throughout the run-time kernel have dependencies on code/facilities outside of the boot kernel, so there are a number of call-sites throughout the boot kernel where inline assembly is used instead. More will be added with subsequent patches that add support for SEV-SNP, so take the opportunity to provide a basic set of helpers that can be used by the boot kernel to reduce reliance on inline assembly. Use boot_* prefix so that it's clear these are helpers specific to the boot kernel to avoid any confusion with the various other MSR read/write helpers. [ bp: Disambiguate parameter names and trim comment. ] Suggested-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Michael Roth <michael.roth@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20220307213356.2797205-6-brijesh.singh@amd.com
27 lines
662 B
C
27 lines
662 B
C
/* SPDX-License-Identifier: GPL-2.0-only */
|
|
/*
|
|
* Helpers/definitions related to MSR access.
|
|
*/
|
|
|
|
#ifndef BOOT_MSR_H
|
|
#define BOOT_MSR_H
|
|
|
|
#include <asm/shared/msr.h>
|
|
|
|
/*
|
|
* 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 */
|