diff options
| -rw-r--r-- | arch/x86/include/asm/cpu.h | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/intel.c | 33 | ||||
| -rw-r--r-- | arch/x86/kvm/vmx/vmx.c | 37 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 12 |
4 files changed, 79 insertions, 9 deletions
diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h index ff6f3ca649b3..dd17c2da1af5 100644 --- a/arch/x86/include/asm/cpu.h +++ b/arch/x86/include/asm/cpu.h @@ -44,6 +44,7 @@ unsigned int x86_stepping(unsigned int sig); 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_guest_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) {} @@ -51,5 +52,10 @@ static inline bool handle_user_split_lock(struct pt_regs *regs, long error_code) { return false; } + +static inline bool handle_guest_split_lock(unsigned long ip) +{ + return false; +} #endif #endif /* _ASM_X86_CPU_H */ diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 9a26e972cdea..bf08d4508ecb 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -21,6 +21,7 @@ #include <asm/elf.h> #include <asm/cpu_device_id.h> #include <asm/cmdline.h> +#include <asm/traps.h> #ifdef CONFIG_X86_64 #include <linux/topology.h> @@ -1066,13 +1067,10 @@ 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) +static void split_lock_warn(unsigned long ip) { - if ((regs->flags & X86_EFLAGS_AC) || 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); /* * Disable the split lock detection for this task so it can make @@ -1081,6 +1079,31 @@ bool handle_user_split_lock(struct pt_regs *regs, long error_code) */ sld_update_msr(false); set_tsk_thread_flag(current, TIF_SLD); +} + +bool handle_guest_split_lock(unsigned long ip) +{ + if (sld_state == sld_warn) { + split_lock_warn(ip); + return true; + } + + pr_warn_once("#AC: %s/%d %s split_lock trap at address: 0x%lx\n", + current->comm, current->pid, + sld_state == sld_fatal ? "fatal" : "bogus", ip); + + current->thread.error_code = 0; + current->thread.trap_nr = X86_TRAP_AC; + force_sig_fault(SIGBUS, BUS_ADRALN, NULL); + return false; +} +EXPORT_SYMBOL_GPL(handle_guest_split_lock); + +bool handle_user_split_lock(struct pt_regs *regs, long error_code) +{ + if ((regs->flags & X86_EFLAGS_AC) || sld_state == sld_fatal) + return false; + split_lock_warn(regs->ip); return true; } diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 8959514eaf0f..83050977490c 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -4588,6 +4588,26 @@ static int handle_machine_check(struct kvm_vcpu *vcpu) return 1; } +/* + * If the host has split lock detection disabled, then #AC is + * unconditionally injected into the guest, which is the pre split lock + * detection behaviour. + * + * If the host has split lock detection enabled then #AC is + * only injected into the guest when: + * - Guest CPL == 3 (user mode) + * - Guest has #AC detection enabled in CR0 + * - Guest EFLAGS has AC bit set + */ +static inline bool guest_inject_ac(struct kvm_vcpu *vcpu) +{ + if (!boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT)) + return true; + + return vmx_get_cpl(vcpu) == 3 && kvm_read_cr0_bits(vcpu, X86_CR0_AM) && + (kvm_get_rflags(vcpu) & X86_EFLAGS_AC); +} + static int handle_exception_nmi(struct kvm_vcpu *vcpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); @@ -4653,9 +4673,6 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu) return handle_rmode_exception(vcpu, ex_no, error_code); switch (ex_no) { - case AC_VECTOR: - kvm_queue_exception_e(vcpu, AC_VECTOR, error_code); - return 1; case DB_VECTOR: dr6 = vmcs_readl(EXIT_QUALIFICATION); if (!(vcpu->guest_debug & @@ -4684,6 +4701,20 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu) kvm_run->debug.arch.pc = vmcs_readl(GUEST_CS_BASE) + rip; kvm_run->debug.arch.exception = ex_no; break; + case AC_VECTOR: + if (guest_inject_ac(vcpu)) { + kvm_queue_exception_e(vcpu, AC_VECTOR, error_code); + return 1; + } + + /* + * Handle split lock. Depending on detection mode this will + * either warn and disable split lock detection for this + * task or force SIGBUS on it. + */ + if (handle_guest_split_lock(kvm_rip_read(vcpu))) + return 1; + fallthrough; default: kvm_run->exit_reason = KVM_EXIT_EXCEPTION; kvm_run->ex.exception = ex_no; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 027dfd278a97..3bf2ecafd027 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5839,6 +5839,7 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt, { struct kvm_host_map map; struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt); + u64 page_line_mask; gpa_t gpa; char *kaddr; bool exchanged; @@ -5853,7 +5854,16 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt, (gpa & PAGE_MASK) == APIC_DEFAULT_PHYS_BASE) goto emul_write; - if (((gpa + bytes - 1) & PAGE_MASK) != (gpa & PAGE_MASK)) + /* + * Emulate the atomic as a straight write to avoid #AC if SLD is + * enabled in the host and the access splits a cache line. + */ + if (boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT)) + page_line_mask = ~(cache_line_size() - 1); + else + page_line_mask = PAGE_MASK; + + if (((gpa + bytes - 1) & page_line_mask) != (gpa & page_line_mask)) goto emul_write; if (kvm_vcpu_map(vcpu, gpa_to_gfn(gpa), &map)) |