KVM: x86/xen: latch long_mode when hypercall page is set up

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b4bcdeb..016a005 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -905,6 +905,11 @@ struct msr_bitmap_range {
        unsigned long *bitmap;
 };
 
+/* Xen emulation context */
+struct kvm_xen {
+       bool long_mode;
+};
+
 enum kvm_irqchip_mode {
        KVM_IRQCHIP_NONE,
        KVM_IRQCHIP_KERNEL,       /* created with KVM_CREATE_IRQCHIP */
@@ -984,6 +989,7 @@ struct kvm_arch {
        struct hlist_head mask_notifier_list;
 
        struct kvm_hv hyperv;
+       struct kvm_xen xen;
 
        #ifdef CONFIG_KVM_MMU_AUDIT
        int audit_point;

diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index a3fd791..55da739 100644 (file)
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -25,6 +25,13 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
        mutex_unlock(&kvm->lock);
 
        switch (data->type) {
+       case KVM_XEN_ATTR_TYPE_LONG_MODE:
+               if (!IS_ENABLED(CONFIG_64BIT) && data->u.long_mode)
+                       return -EINVAL;
+
+               kvm->arch.xen.long_mode = !!data->u.long_mode;
+               r = 0;
+               break;
        default:
                break;
        }
@@ -40,6 +47,10 @@ int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
        mutex_lock(&kvm->lock);
 
        switch (data->type) {
+       case KVM_XEN_ATTR_TYPE_LONG_MODE:
+               data->u.long_mode = kvm->arch.xen.long_mode;
+               r = 0;
+               break;
        default:
                break;
        }
@@ -53,6 +64,10 @@ int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data)
        struct kvm *kvm = vcpu->kvm;
        u32 page_num = data & ~PAGE_MASK;
        u64 page_addr = data & PAGE_MASK;
+       bool lm = is_long_mode(vcpu);
+
+       /* Latch long_mode for shared_info pages etc. */
+       vcpu->kvm->arch.xen.long_mode = lm;
 
        /*
         * If Xen hypercall intercept is enabled, fill the hypercall
@@ -87,7 +102,6 @@ int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data)
                                return 1;
                }
        } else {
-               int lm = is_long_mode(vcpu);
                u64 blob_addr = lm ? kvm->arch.xen_hvm_config.blob_addr_64
                                   : kvm->arch.xen_hvm_config.blob_addr_32;
                u8 blob_size = lm ? kvm->arch.xen_hvm_config.blob_size_64

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 3347967..1164495 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1594,10 +1594,13 @@ struct kvm_xen_hvm_attr {
        __u16 type;
        __u16 pad[3];
        union {
+               __u8 long_mode;
                __u64 pad[8];
        } u;
 };
 
+#define KVM_XEN_ATTR_TYPE_LONG_MODE            0x0
+
 /* Secure Encrypted Virtualization command */
 enum sev_cmd_id {
        /* Guest initialization commands */