Messages in this thread | | | Subject | Re: [PATCH v7 6/6] x86/split_lock: Fix the split lock #AC handling when running as guest | From | Sathyanarayanan Kuppuswamy <> | Date | Wed, 13 Oct 2021 14:32:46 -0700 |
| |
+ Xiaoyao
On 10/13/21 1:30 PM, Sean Christopherson wrote: > On Tue, Oct 05, 2021, Kuppuswamy Sathyanarayanan wrote: >> From: Xiaoyao Li <xiaoyao.li@intel.com> >> >> If running as guest and hypervisor enables >> MSR_TEST_CTRL.SPLIT_LOCK_DETECT during its running, it can get split >> lock #AC even though sld_state is sld_off. > That's a hypervisor bug, no? The hypervisor should never inject a fault that > the guest cannot reasonably expect. > >> For kernel mode #AC, it always dies("split lock"), no more action >> needed. >> >> For user mode #AC, it should treat sld_off (default state when feature >> is not available) as fatal as well. >> >> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com> >> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> >> --- >> arch/x86/kernel/cpu/intel.c | 7 ++++++- >> 1 file changed, 6 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c >> index 01d7935feaed..47f0bc95ce2a 100644 >> --- a/arch/x86/kernel/cpu/intel.c >> +++ b/arch/x86/kernel/cpu/intel.c >> @@ -1190,7 +1190,12 @@ static void bus_lock_init(void) >> >> bool handle_user_split_lock(struct pt_regs *regs, long error_code) >> { >> - if ((regs->flags & X86_EFLAGS_AC) || sld_state == sld_fatal) >> + /* >> + * In virtualization environment, it can get split lock #AC even when >> + * sld_off but hypervisor enables it. >> + * Thus only handles when sld_warn explicitly. >> + */ >> + if ((regs->flags & X86_EFLAGS_AC) || sld_state != sld_warn) >> return false; >> split_lock_warn(regs->ip); >> return true; >> -- >> 2.25.1 >> -- Sathyanarayanan Kuppuswamy Linux Kernel Developer
| |