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]> --- 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] v10: - New in this version. --- arch/x86/kvm/xen.c | 36 +++++++++++++++++++++++++++++------- 1 file changed, 29 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index 9351b32cfcba..3aa452a71890 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -623,10 +623,20 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data) if (!IS_ENABLED(CONFIG_64BIT) && data->u.long_mode) { r = -EINVAL; } else { + bool lm = !!data->u.long_mode; + mutex_lock(&kvm->arch.xen.xen_lock); - kvm->arch.xen.long_mode = !!data->u.long_mode; + 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. + */ + r = kvm->arch.xen.shinfo_cache.active ? + kvm_xen_shared_info_init(kvm) : 0; + } mutex_unlock(&kvm->arch.xen.xen_lock); - r = 0; } break; @@ -648,9 +658,6 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data) srcu_read_unlock(&kvm->srcu, idx); - if (!r && kvm->arch.xen.shinfo_cache.active) - r = kvm_xen_shared_info_init(kvm); - mutex_unlock(&kvm->arch.xen.xen_lock); break; } @@ -1101,9 +1108,24 @@ 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
