Sean Christopherson <sean.j.christopherson@xxxxxxxxx> writes:
> From: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
>
> In the future, KVM will use handle_user_split_lock() to handle #AC
> caused by split lock in guest. Due to the fact that KVM doesn't have
> a @regs context and will pre-check EFLAGS.AC, move the EFLAGS.AC check
> to do_alignment_check().
>
> Suggested-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
> Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> ---
> arch/x86/include/asm/cpu.h | 4 ++--
> arch/x86/kernel/cpu/intel.c | 7 ++++---
> arch/x86/kernel/traps.c | 2 +-
> 3 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
> index ff6f3ca649b3..ff567afa6ee1 100644
> --- a/arch/x86/include/asm/cpu.h
> +++ b/arch/x86/include/asm/cpu.h
> @@ -43,11 +43,11 @@ unsigned int x86_stepping(unsigned int sig);
> #ifdef CONFIG_CPU_SUP_INTEL
> extern void __init cpu_set_core_cap_bits(struct cpuinfo_x86 *c);
> extern void switch_to_sld(unsigned long tifn);
> -extern bool handle_user_split_lock(struct pt_regs *regs, long error_code);
> +extern bool handle_user_split_lock(unsigned long ip);
> #else
> static inline void __init cpu_set_core_cap_bits(struct cpuinfo_x86 *c) {}
> static inline void switch_to_sld(unsigned long tifn) {}
> -static inline bool handle_user_split_lock(struct pt_regs *regs, long error_code)
> +static inline bool handle_user_split_lock(unsigned long ip)
This is necessary because VMX can be compiled without CPU_SUP_INTEL?
> {
> return false;
> }
> diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
> index 9a26e972cdea..7688f51aabdb 100644
> --- a/arch/x86/kernel/cpu/intel.c
> +++ b/arch/x86/kernel/cpu/intel.c
> @@ -1066,13 +1066,13 @@ static void split_lock_init(void)
> split_lock_verify_msr(sld_state != sld_off);
> }
>
> -bool handle_user_split_lock(struct pt_regs *regs, long error_code)
> +bool handle_user_split_lock(unsigned long ip)
> {
> - if ((regs->flags & X86_EFLAGS_AC) || sld_state == sld_fatal)
> + if (sld_state == sld_fatal)
> return false;
>
> pr_warn_ratelimited("#AC: %s/%d took a split_lock trap at address: 0x%lx\n",
> - current->comm, current->pid, regs->ip);
> + current->comm, current->pid, ip);
So this returns true even in the case that sld_state == off.
Should never happen, but I rather have an extra check and be both
verbose and correct. See the variant I did.
Thanks,
tglx
