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KVM support: detect KVM and avoid touching unimplemented MSRs

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This commit is contained in:
Balazs Gerofi
2016-05-26 01:11:08 +09:00
parent 435e2bdeb4
commit 14ec92518e
2 changed files with 31 additions and 0 deletions
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27
arch/x86/kernel/cpu.c
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@@ -79,6 +79,7 @@ static unsigned int (*lapic_read)(int reg);
static void (*lapic_icr_write)(unsigned int h, unsigned int l);
static void (*lapic_wait_icr_idle)(void);
void (*x86_issue_ipi)(unsigned int apicid, unsigned int low);
int running_on_kvm(void);
void init_processors_local(int max_id);
void assign_processor_id(void);
@@ -454,6 +455,8 @@ void init_pstate_and_turbo(void)
uint64_t value;
uint64_t eax, ecx;
if (running_on_kvm()) return;
asm volatile("cpuid" : "=a" (eax), "=c" (ecx) : "a" (0x6) : "%rbx", "%rdx");
if (!(ecx & 0x01)) {
/* P-states and/or Turbo Boost are not supported. */
@@ -619,6 +622,9 @@ static void init_smp_processor(void)
reload_gdt(&v->gdt_ptr);
set_kstack((unsigned long)get_x86_this_cpu_kstack());
/* MSR_IA32_TSC_AUX on KVM seems broken */
if (running_on_kvm()) return;
#define MSR_IA32_TSC_AUX 0xc0000103
wrmsr(MSR_IA32_TSC_AUX, node_cpu);
}
@@ -1740,4 +1746,25 @@ out:
return error;
} /* arch_get_cpu_mapping() */
#define KVM_CPUID_SIGNATURE 0x40000000
int running_on_kvm(void) {
static const char signature[12] = "KVMKVMKVM\0\0";
const uint32_t *sigptr = (const uint32_t *)signature;
uint64_t op;
uint64_t eax;
uint64_t ebx;
uint64_t ecx;
uint64_t edx;
op = KVM_CPUID_SIGNATURE;
asm volatile("cpuid" : "=a"(eax),"=b"(ebx),"=c"(ecx),"=d"(edx) : "a" (op));
if (ebx == sigptr[0] && ecx == sigptr[1] && edx == sigptr[2]) {
return 1;
}
return 0;
}
/*** end of file ***/