diff options
| author | Chao Gao <chao.gao@intel.com> | 2025-08-11 19:55:13 -0700 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2025-08-19 11:59:51 -0700 |
| commit | c26675447faff8c4ddc1dc5d2cd28326b8181aaf (patch) | |
| tree | f6e20989f503d7051968d2c438675cbd3b8ffb90 | |
| parent | 41f6710f99f4337924e3929e8e7a51c74f800b91 (diff) | |
KVM: x86: Zero XSTATE components on INIT by iterating over supported features
Tweak the code a bit to facilitate resetting more xstate components in
the future, e.g., CET's xstate-managed MSRs.
No functional change intended.
Suggested-by: Sean Christopherson <seanjc@google.com>
Tested-by: Mathias Krause <minipli@grsecurity.net>
Tested-by: John Allen <john.allen@amd.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Tested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Link: https://lore.kernel.org/r/20250812025606.74625-6-chao.gao@intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
| -rw-r--r-- | arch/x86/kvm/x86.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index d398ee84c8f3..8bfba7d8f750 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -12401,6 +12401,8 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu) static void kvm_xstate_reset(struct kvm_vcpu *vcpu, bool init_event) { struct fpstate *fpstate = vcpu->arch.guest_fpu.fpstate; + u64 xfeatures_mask; + int i; /* * Guest FPU state is zero allocated and so doesn't need to be manually @@ -12414,16 +12416,20 @@ static void kvm_xstate_reset(struct kvm_vcpu *vcpu, bool init_event) * are unchanged. Currently, the only components that are zeroed and * supported by KVM are MPX related. */ - if (!kvm_mpx_supported()) + xfeatures_mask = (kvm_caps.supported_xcr0 | kvm_caps.supported_xss) & + (XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR); + if (!xfeatures_mask) return; + BUILD_BUG_ON(sizeof(xfeatures_mask) * BITS_PER_BYTE <= XFEATURE_MAX); + /* * All paths that lead to INIT are required to load the guest's FPU * state (because most paths are buried in KVM_RUN). */ kvm_put_guest_fpu(vcpu); - fpstate_clear_xstate_component(fpstate, XFEATURE_BNDREGS); - fpstate_clear_xstate_component(fpstate, XFEATURE_BNDCSR); + for_each_set_bit(i, (unsigned long *)&xfeatures_mask, XFEATURE_MAX) + fpstate_clear_xstate_component(fpstate, i); kvm_load_guest_fpu(vcpu); } |