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x86, msr: Add rd/wrmsr interfaces with preset registers

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native_{rdmsr,wrmsr}_safe_regs are two new interfaces which allow
presetting of a subset of eight x86 GPRs before executing the rd/wrmsr
instructions. This is needed at least on AMD K8 for accessing an erratum
workaround MSR.

Originally based on an idea by H. Peter Anvin.

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
LKML-Reference: <1251705011-18636-1-git-send-email-petkovbb@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
Borislav Petkov
2009-08-31 09:50:09 +02:00
committed by H. Peter Anvin
parent 366d19e181
commit 132ec92f3f
5 changed files with 130 additions and 0 deletions
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16
arch/x86/include/asm/paravirt.h
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@@ -168,7 +168,9 @@ struct pv_cpu_ops {
err = 0/-EFAULT. wrmsr returns 0/-EFAULT. */
u64 (*read_msr_amd)(unsigned int msr, int *err);
u64 (*read_msr)(unsigned int msr, int *err);
int (*rdmsr_regs)(u32 *regs);
int (*write_msr)(unsigned int msr, unsigned low, unsigned high);
int (*wrmsr_regs)(u32 *regs);
u64 (*read_tsc)(void);
u64 (*read_pmc)(int counter);
@@ -820,6 +822,12 @@ static inline u64 paravirt_read_msr(unsigned msr, int *err)
{
return PVOP_CALL2(u64, pv_cpu_ops.read_msr, msr, err);
}
static inline int paravirt_rdmsr_regs(u32 *regs)
{
return PVOP_CALL1(int, pv_cpu_ops.rdmsr_regs, regs);
}
static inline u64 paravirt_read_msr_amd(unsigned msr, int *err)
{
return PVOP_CALL2(u64, pv_cpu_ops.read_msr_amd, msr, err);
@@ -829,6 +837,11 @@ static inline int paravirt_write_msr(unsigned msr, unsigned low, unsigned high)
return PVOP_CALL3(int, pv_cpu_ops.write_msr, msr, low, high);
}
static inline int paravirt_wrmsr_regs(u32 *regs)
{
return PVOP_CALL1(int, pv_cpu_ops.wrmsr_regs, regs);
}
/* These should all do BUG_ON(_err), but our headers are too tangled. */
#define rdmsr(msr, val1, val2) \
do { \
@@ -862,6 +875,9 @@ do { \
_err; \
})
#define rdmsr_safe_regs(regs) paravirt_rdmsr_regs(regs)
#define wrmsr_safe_regs(regs) paravirt_wrmsr_regs(regs)
static inline int rdmsrl_safe(unsigned msr, unsigned long long *p)
{
int err;