From: Paul Durrant <[email protected]> If the shared_info PFN cache has already been initialized then the content of the shared_info page needs to be re-initialized whenever the guest mode is (re)set. Setting the guest mode is either done explicitly by the VMM via the KVM_XEN_ATTR_TYPE_LONG_MODE attribute, or implicitly when the guest writes the MSR to set up the hypercall page.
Signed-off-by: Paul Durrant <[email protected]> Reviewed-by: David Woodhouse <[email protected]> --- Cc: Sean Christopherson <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Dave Hansen <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: David Woodhouse <[email protected]> Cc: [email protected] v12: - Fix missing update of return value if mode is not actually changed. v11: - Drop the hunk removing the call to kvm_xen_shared_info_init() when KVM_XEN_ATTR_TYPE_SHARED_INFO is set; it was a mistake and causes self- test failures. v10: - New in this version. --- arch/x86/kvm/xen.c | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index df53fea73747..d595d476a5b3 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -625,8 +625,16 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data) } else { mutex_lock(&kvm->arch.xen.xen_lock); kvm->arch.xen.long_mode = !!data->u.long_mode; + + /* + * Re-initialize shared_info to put the wallclock in the + * correct place. Whilst it's not necessary to do this + * unless the mode is actually changed, it does no harm + * to make the call anyway. + */ + r = kvm->arch.xen.shinfo_cache.active ? + kvm_xen_shared_info_init(kvm) : 0; mutex_unlock(&kvm->arch.xen.xen_lock); - r = 0; } break; @@ -1101,9 +1109,24 @@ int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data) u32 page_num = data & ~PAGE_MASK; u64 page_addr = data & PAGE_MASK; bool lm = is_long_mode(vcpu); + int r = 0; + + mutex_lock(&kvm->arch.xen.xen_lock); + if (kvm->arch.xen.long_mode != lm) { + kvm->arch.xen.long_mode = lm; + + /* + * Re-initialize shared_info to put the wallclock in the + * correct place. + */ + if (kvm->arch.xen.shinfo_cache.active && + kvm_xen_shared_info_init(kvm)) + r = 1; + } + mutex_unlock(&kvm->arch.xen.xen_lock); - /* Latch long_mode for shared_info pages etc. */ - vcpu->kvm->arch.xen.long_mode = lm; + if (r) + return r; /* * If Xen hypercall intercept is enabled, fill the hypercall -- 2.39.2
