| Message ID | 20250201011400.669483-3-seanjc@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86/xen: Restrict hypercall MSR index | expand |
On 01/02/2025 01:13, Sean Christopherson wrote: > Add a helper to detect writes to the Xen hypercall page MSR, and provide a > stub for CONFIG_KVM_XEN=n to optimize out the check for kernels built > without Xen support. > > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > arch/x86/kvm/x86.c | 2 +- > arch/x86/kvm/xen.h | 10 ++++++++++ > 2 files changed, 11 insertions(+), 1 deletion(-) > Reviewed-by: Paul Durrant <paul@xen.org>
On Fri, 2025-01-31 at 17:13 -0800, Sean Christopherson wrote: > Add a helper to detect writes to the Xen hypercall page MSR, and provide a > stub for CONFIG_KVM_XEN=n to optimize out the check for kernels built > without Xen support. > > Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b2d9a16fd4d3..f13d9d3f7c60 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3733,7 +3733,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) u32 msr = msr_info->index; u64 data = msr_info->data; - if (msr && msr == vcpu->kvm->arch.xen_hvm_config.msr) + if (kvm_xen_is_hypercall_page_msr(vcpu->kvm, msr)) return kvm_xen_write_hypercall_page(vcpu, data); switch (msr) { diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h index f5841d9000ae..e92e06926f76 100644 --- a/arch/x86/kvm/xen.h +++ b/arch/x86/kvm/xen.h @@ -56,6 +56,11 @@ static inline bool kvm_xen_msr_enabled(struct kvm *kvm) kvm->arch.xen_hvm_config.msr; } +static inline bool kvm_xen_is_hypercall_page_msr(struct kvm *kvm, u32 msr) +{ + return msr && msr == kvm->arch.xen_hvm_config.msr; +} + static inline bool kvm_xen_hypercall_enabled(struct kvm *kvm) { return static_branch_unlikely(&kvm_xen_enabled.key) && @@ -124,6 +129,11 @@ static inline bool kvm_xen_msr_enabled(struct kvm *kvm) return false; } +static inline bool kvm_xen_is_hypercall_page_msr(struct kvm *kvm, u32 msr) +{ + return false; +} + static inline bool kvm_xen_hypercall_enabled(struct kvm *kvm) { return false;
Add a helper to detect writes to the Xen hypercall page MSR, and provide a stub for CONFIG_KVM_XEN=n to optimize out the check for kernels built without Xen support. Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/kvm/x86.c | 2 +- arch/x86/kvm/xen.h | 10 ++++++++++ 2 files changed, 11 insertions(+), 1 deletion(-)