Commit 132ec92f authored by Borislav Petkov's avatar Borislav Petkov Committed by H. Peter Anvin

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

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: default avatarBorislav Petkov <petkovbb@gmail.com>
LKML-Reference: <1251705011-18636-1-git-send-email-petkovbb@gmail.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 366d19e1
......@@ -113,6 +113,9 @@ notrace static inline int native_write_msr_safe(unsigned int msr,
extern unsigned long long native_read_tsc(void);
extern int native_rdmsr_safe_regs(u32 *regs);
extern int native_wrmsr_safe_regs(u32 *regs);
static __always_inline unsigned long long __native_read_tsc(void)
{
DECLARE_ARGS(val, low, high);
......@@ -189,6 +192,16 @@ static inline int rdmsrl_amd_safe(unsigned msr, unsigned long long *p)
return err;
}
static inline int rdmsr_safe_regs(u32 *regs)
{
return native_rdmsr_safe_regs(regs);
}
static inline int wrmsr_safe_regs(u32 *regs)
{
return native_wrmsr_safe_regs(regs);
}
#define rdtscl(low) \
((low) = (u32)__native_read_tsc())
......
......@@ -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;
......
......@@ -362,8 +362,10 @@ struct pv_cpu_ops pv_cpu_ops = {
#endif
.wbinvd = native_wbinvd,
.read_msr = native_read_msr_safe,
.rdmsr_regs = native_rdmsr_safe_regs,
.read_msr_amd = native_read_msr_amd_safe,
.write_msr = native_write_msr_safe,
.wrmsr_regs = native_wrmsr_safe_regs,
.read_tsc = native_read_tsc,
.read_pmc = native_read_pmc,
.read_tscp = native_read_tscp,
......
......@@ -8,6 +8,7 @@ lib-y := delay.o
lib-y += thunk_$(BITS).o
lib-y += usercopy_$(BITS).o getuser.o putuser.o
lib-y += memcpy_$(BITS).o
lib-y += msr-reg.o
ifeq ($(CONFIG_X86_32),y)
obj-y += atomic64_32.o
......
#include <linux/linkage.h>
#include <linux/errno.h>
#include <asm/asm.h>
#include <asm/msr.h>
#ifdef CONFIG_X86_64
/*
* int native_{rdmsr,wrmsr}_safe_regs(u32 gprs[8]);
*
* reg layout: u32 gprs[eax, ecx, edx, ebx, esp, ebp, esi, edi]
*
*/
.macro op_safe_regs op:req
ENTRY(native_\op\()_safe_regs)
push %rbx
push %rbp
push $0 /* Return value */
push %rdi
movl (%rdi), %eax
movl 4(%rdi), %ecx
movl 8(%rdi), %edx
movl 12(%rdi), %ebx
movl 20(%rdi), %ebp
movl 24(%rdi), %esi
movl 28(%rdi), %edi
1: \op
2: movl %edi, %r10d
pop %rdi
movl %eax, (%rdi)
movl %ecx, 4(%rdi)
movl %edx, 8(%rdi)
movl %ebx, 12(%rdi)
movl %ebp, 20(%rdi)
movl %esi, 24(%rdi)
movl %r10d, 28(%rdi)
pop %rax
pop %rbp
pop %rbx
ret
3:
movq $-EIO, 8(%rsp)
jmp 2b
.section __ex_table,"ax"
.balign 4
.quad 1b, 3b
.previous
ENDPROC(native_\op\()_safe_regs)
.endm
#else /* X86_32 */
.macro op_safe_regs op:req
ENTRY(native_\op\()_safe_regs)
push %ebx
push %ebp
push %esi
push %edi
push $0 /* Return value */
push %eax
movl 4(%eax), %ecx
movl 8(%eax), %edx
movl 12(%eax), %ebx
movl 20(%eax), %ebp
movl 24(%eax), %esi
movl 28(%eax), %edi
movl (%eax), %eax
1: \op
2: push %eax
movl 4(%esp), %eax
pop (%eax)
addl $4, %esp
movl %ecx, 4(%eax)
movl %edx, 8(%eax)
movl %ebx, 12(%eax)
movl %ebp, 20(%eax)
movl %esi, 24(%eax)
movl %edi, 28(%eax)
pop %eax
pop %edi
pop %esi
pop %ebp
pop %ebx
ret
3:
movl $-EIO, 4(%esp)
jmp 2b
.section __ex_table,"ax"
.balign 4
.long 1b, 3b
.previous
ENDPROC(native_\op\()_safe_regs)
.endm
#endif
op_safe_regs rdmsr
op_safe_regs wrmsr
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