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authorThomas Gleixner <tglx@linutronix.de>2020-04-10 13:54:00 +0200
committerBorislav Petkov <bp@suse.de>2020-04-11 16:39:30 +0200
commitd7e94dbdac1a40924626b0efc7ff530c8baf5e4a (patch)
tree7e41876bdd753a6e9b0e6911cb03bcee99a1c320
parent5b8b9d0c6d0e0f1993c6c56deaf9646942c49d94 (diff)
downloadlinux-d7e94dbdac1a40924626b0efc7ff530c8baf5e4a.tar.gz
linux-d7e94dbdac1a40924626b0efc7ff530c8baf5e4a.tar.xz
x86/split_lock: Provide handle_guest_split_lock()
Without at least minimal handling for split lock detection induced #AC, VMX will just run into the same problem as the VMWare hypervisor, which was reported by Kenneth. It will inject the #AC blindly into the guest whether the guest is prepared or not. Provide a function for guest mode which acts depending on the host SLD mode. If mode == sld_warn, treat it like user space, i.e. emit a warning, disable SLD and mark the task accordingly. Otherwise force SIGBUS. [ bp: Add a !CPU_SUP_INTEL stub for handle_guest_split_lock(). ] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Link: https://lkml.kernel.org/r/20200410115516.978037132@linutronix.de Link: https://lkml.kernel.org/r/20200402123258.895628824@linutronix.de
-rw-r--r--arch/x86/include/asm/cpu.h6
-rw-r--r--arch/x86/kernel/cpu/intel.c33
2 files changed, 34 insertions, 5 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;
}