diff options
| author | Sean Christopherson <seanjc@google.com> | 2023-10-18 12:36:17 -0700 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2023-11-30 12:51:14 -0800 |
| commit | 770d6aa2e416fd26f0356e258c77a37574ad9b8c (patch) | |
| tree | 157c1317e0d9bca133d64f8003c39115d0c426f2 | |
| parent | 176bfc5b17fee327585583a427e2857d9dfd8f68 (diff) | |
KVM: SVM: Explicitly require FLUSHBYASID to enable SEV support
Add a sanity check that FLUSHBYASID is available if SEV is supported in
hardware, as SEV (and beyond) guests are bound to a single ASID, i.e. KVM
can't "flush" by assigning a new, fresh ASID to the guest. If FLUSHBYASID
isn't supported for some bizarre reason, KVM would completely fail to do
TLB flushes for SEV+ guests (see pre_svm_run() and pre_sev_run()).
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20231018193617.1895752-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
| -rw-r--r-- | arch/x86/kvm/svm/sev.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 4900c078045a..d0c580607f00 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2191,10 +2191,13 @@ void __init sev_hardware_setup(void) /* * SEV must obviously be supported in hardware. Sanity check that the * CPU supports decode assists, which is mandatory for SEV guests to - * support instruction emulation. + * support instruction emulation. Ditto for flushing by ASID, as SEV + * guests are bound to a single ASID, i.e. KVM can't rotate to a new + * ASID to effect a TLB flush. */ if (!boot_cpu_has(X86_FEATURE_SEV) || - WARN_ON_ONCE(!boot_cpu_has(X86_FEATURE_DECODEASSISTS))) + WARN_ON_ONCE(!boot_cpu_has(X86_FEATURE_DECODEASSISTS)) || + WARN_ON_ONCE(!boot_cpu_has(X86_FEATURE_FLUSHBYASID))) goto out; /* Retrieve SEV CPUID information */ |