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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
26 lines
662 B
C
26 lines
662 B
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Helpers/definitions related to MSR access.
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*/
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#ifndef BOOT_MSR_H
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#define BOOT_MSR_H
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#include <asm/shared/msr.h>
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/*
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* The kernel proper already defines rdmsr()/wrmsr(), but they are not for the
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* boot kernel since they rely on tracepoint/exception handling infrastructure
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* that's not available here.
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*/
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static inline void boot_rdmsr(unsigned int reg, struct msr *m)
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{
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asm volatile("rdmsr" : "=a" (m->l), "=d" (m->h) : "c" (reg));
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}
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static inline void boot_wrmsr(unsigned int reg, const struct msr *m)
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{
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asm volatile("wrmsr" : : "c" (reg), "a"(m->l), "d" (m->h) : "memory");
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}
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#endif /* BOOT_MSR_H */
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