mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-25 21:54:06 +08:00
x86/msr: Carry on after a non-"safe" MSR access fails
This demotes an OOPS and likely panic due to a failed non-"safe" MSR access to a WARN_ONCE() and, for RDMSR, a return value of zero. To be clear, this type of failure should *not* happen. This patch exists to minimize the chance of nasty undebuggable failures happening when a CONFIG_PARAVIRT=y bug in the non-"safe" MSR helpers gets fixed. Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Andy Lutomirski <luto@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: KVM list <kvm@vger.kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: xen-devel <Xen-devel@lists.xen.org> Link: http://lkml.kernel.org/r/26567b216aae70e795938f4b567eace5a0eb90ba.1459605520.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
parent
c2ee03b2a9
commit
fbd704374d
@ -84,7 +84,10 @@ static inline unsigned long long native_read_msr(unsigned int msr)
|
||||
{
|
||||
DECLARE_ARGS(val, low, high);
|
||||
|
||||
asm volatile("rdmsr" : EAX_EDX_RET(val, low, high) : "c" (msr));
|
||||
asm volatile("1: rdmsr\n"
|
||||
"2:\n"
|
||||
_ASM_EXTABLE_HANDLE(1b, 2b, ex_handler_rdmsr_unsafe)
|
||||
: EAX_EDX_RET(val, low, high) : "c" (msr));
|
||||
if (msr_tracepoint_active(__tracepoint_read_msr))
|
||||
do_trace_read_msr(msr, EAX_EDX_VAL(val, low, high), 0);
|
||||
return EAX_EDX_VAL(val, low, high);
|
||||
@ -111,7 +114,10 @@ static inline unsigned long long native_read_msr_safe(unsigned int msr,
|
||||
static inline void native_write_msr(unsigned int msr,
|
||||
unsigned low, unsigned high)
|
||||
{
|
||||
asm volatile("wrmsr" : : "c" (msr), "a"(low), "d" (high) : "memory");
|
||||
asm volatile("1: wrmsr\n"
|
||||
"2:\n"
|
||||
_ASM_EXTABLE_HANDLE(1b, 2b, ex_handler_wrmsr_unsafe)
|
||||
: : "c" (msr), "a"(low), "d" (high) : "memory");
|
||||
if (msr_tracepoint_active(__tracepoint_read_msr))
|
||||
do_trace_write_msr(msr, ((u64)high << 32 | low), 0);
|
||||
}
|
||||
|
@ -43,6 +43,33 @@ bool ex_handler_ext(const struct exception_table_entry *fixup,
|
||||
}
|
||||
EXPORT_SYMBOL(ex_handler_ext);
|
||||
|
||||
bool ex_handler_rdmsr_unsafe(const struct exception_table_entry *fixup,
|
||||
struct pt_regs *regs, int trapnr)
|
||||
{
|
||||
WARN_ONCE(1, "unchecked MSR access error: RDMSR from 0x%x\n",
|
||||
(unsigned int)regs->cx);
|
||||
|
||||
/* Pretend that the read succeeded and returned 0. */
|
||||
regs->ip = ex_fixup_addr(fixup);
|
||||
regs->ax = 0;
|
||||
regs->dx = 0;
|
||||
return true;
|
||||
}
|
||||
EXPORT_SYMBOL(ex_handler_rdmsr_unsafe);
|
||||
|
||||
bool ex_handler_wrmsr_unsafe(const struct exception_table_entry *fixup,
|
||||
struct pt_regs *regs, int trapnr)
|
||||
{
|
||||
WARN_ONCE(1, "unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08x%08x)\n",
|
||||
(unsigned int)regs->cx,
|
||||
(unsigned int)regs->dx, (unsigned int)regs->ax);
|
||||
|
||||
/* Pretend that the write succeeded. */
|
||||
regs->ip = ex_fixup_addr(fixup);
|
||||
return true;
|
||||
}
|
||||
EXPORT_SYMBOL(ex_handler_wrmsr_unsafe);
|
||||
|
||||
bool ex_has_fault_handler(unsigned long ip)
|
||||
{
|
||||
const struct exception_table_entry *e;
|
||||
|
Loading…
Reference in New Issue
Block a user