diff options
| author |   Sean Christopherson <seanjc@google.com> | 2021-11-04 18:22:39 +0000 |
|---|---|---|
| committer |   Wei Liu <wei.liu@kernel.org> | 2021-11-15 12:37:08 +0000 |
| commit | f3e613e72f66226b3bea1046c1b864f67a3000a4 (patch) | |
| tree | 2142a28f2026a9ca83874b7f5ae65efd1ab19e55 /arch/x86/kernel/cpu/mshyperv.c | |
| parent | x86/hyperv: Fix NULL deref in set_hv_tscchange_cb() if Hyper-V setup fails (diff) | |
| download | linux-dev-f3e613e72f66226b3bea1046c1b864f67a3000a4.tar.xz linux-dev-f3e613e72f66226b3bea1046c1b864f67a3000a4.zip | |
x86/hyperv: Move required MSRs check to initial platform probing
Explicitly check for MSR_HYPERCALL and MSR_VP_INDEX support when probing
for running as a Hyper-V guest instead of waiting until hyperv_init() to
detect the bogus configuration. Add messages to give the admin a heads
up that they are likely running on a broken virtual machine setup.
At best, silently disabling Hyper-V is confusing and difficult to debug,
e.g. the kernel _says_ it's using all these fancy Hyper-V features, but
always falls back to the native versions. At worst, the half baked setup
will crash/hang the kernel.
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20211104182239.1302956-3-seanjc@google.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Diffstat (limited to 'arch/x86/kernel/cpu/mshyperv.c')
| -rw-r--r-- | arch/x86/kernel/cpu/mshyperv.c | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index 4794b716ec79..ff55df60228f 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -163,12 +163,22 @@ static uint32_t __init ms_hyperv_platform(void) cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS, &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]); - if (eax >= HYPERV_CPUID_MIN && - eax <= HYPERV_CPUID_MAX && - !memcmp("Microsoft Hv", hyp_signature, 12)) - return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS; + if (eax < HYPERV_CPUID_MIN || eax > HYPERV_CPUID_MAX || + memcmp("Microsoft Hv", hyp_signature, 12)) + return 0; - return 0; + /* HYPERCALL and VP_INDEX MSRs are mandatory for all features. */ + eax = cpuid_eax(HYPERV_CPUID_FEATURES); + if (!(eax & HV_MSR_HYPERCALL_AVAILABLE)) { + pr_warn("x86/hyperv: HYPERCALL MSR not available.\n"); + return 0; + } + if (!(eax & HV_MSR_VP_INDEX_AVAILABLE)) { + pr_warn("x86/hyperv: VP_INDEX MSR not available.\n"); + return 0; + } + + return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS; } static unsigned char hv_get_nmi_reason(void) |