From: Paul Durrant pdurrant@amazon.com
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 pdurrant@amazon.com --- Cc: Sean Christopherson seanjc@google.com Cc: Paolo Bonzini pbonzini@redhat.com Cc: Thomas Gleixner tglx@linutronix.de Cc: Ingo Molnar mingo@redhat.com Cc: Borislav Petkov bp@alien8.de Cc: Dave Hansen dave.hansen@linux.intel.com Cc: "H. Peter Anvin" hpa@zytor.com Cc: David Woodhouse dwmw2@infradead.org Cc: x86@kernel.org
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