diff options
| -rw-r--r-- | docs/misc/xen-command-line.markdown | 10 | ||||
| -rw-r--r-- | xen/arch/x86/cpu/amd.c | 8 | ||||
| -rw-r--r-- | xen/include/asm-x86/amd.h | 3 |
3 files changed, 21 insertions, 0 deletions
diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown index 1f3faaa6de..7ceaa3b555 100644 --- a/docs/misc/xen-command-line.markdown +++ b/docs/misc/xen-command-line.markdown @@ -126,6 +126,16 @@ Override Xen's logic for choosing the APIC driver. By default, if there are more than 8 CPUs, Xen will switch to `bigsmp` over `default`. +### allow\_unsafe +> `= <boolean>` + +Force boot on potentially unsafe systems. By default Xen will refuse to boot on +systems with the following errata: + +* AMD Erratum 121. Processors with this erratum are subject to a guest + triggerable Denial of Service. Override only if you trust all of your PV + guests. + ### apic\_verbosity > `= verbose | debug` diff --git a/xen/arch/x86/cpu/amd.c b/xen/arch/x86/cpu/amd.c index b8c3a32480..81f7196827 100644 --- a/xen/arch/x86/cpu/amd.c +++ b/xen/arch/x86/cpu/amd.c @@ -32,6 +32,9 @@ static char opt_famrev[14]; string_param("cpuid_mask_cpu", opt_famrev); +static bool_t opt_allow_unsafe; +boolean_param("allow_unsafe", opt_allow_unsafe); + static inline void wrmsr_amd(unsigned int index, unsigned int lo, unsigned int hi) { @@ -493,6 +496,11 @@ static void __devinit init_amd(struct cpuinfo_x86 *c) clear_bit(X86_FEATURE_MWAIT, c->x86_capability); #ifdef __x86_64__ + if (cpu_has_amd_erratum(c, AMD_ERRATUM_121) && !opt_allow_unsafe) + panic("Xen will not boot on this CPU for security reasons.\n" + "Pass \"allow_unsafe\" if you're trusting all your" + " (PV) guest kernels.\n"); + /* AMD CPUs do not support SYSENTER outside of legacy mode. */ clear_bit(X86_FEATURE_SEP, c->x86_capability); diff --git a/xen/include/asm-x86/amd.h b/xen/include/asm-x86/amd.h index 9a7fa3be65..94bd9cce09 100644 --- a/xen/include/asm-x86/amd.h +++ b/xen/include/asm-x86/amd.h @@ -127,6 +127,9 @@ #define AMD_MODEL_RANGE_START(range) (((range) >> 12) & 0xfff) #define AMD_MODEL_RANGE_END(range) ((range) & 0xfff) +#define AMD_ERRATUM_121 \ + AMD_LEGACY_ERRATUM(AMD_MODEL_RANGE(0x0f, 0x0, 0x0, 0x3f, 0xf)) + #define AMD_ERRATUM_170 \ AMD_LEGACY_ERRATUM(AMD_MODEL_RANGE(0x0f, 0x0, 0x0, 0x67, 0xf)) |