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 9de3229e91e116b1acaf36aa646d1eca80881da4..c9a4feaee2e710245ef9c24ef71976e727419ac5 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -890,6 +890,11 @@ 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 */
@@ -969,6 +974,7 @@ 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 c0b2c67e02352d7203991e388065313188fd216a..52cb9e4655421cd57424ff2a74025c322382b928 100644 (file)
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -21,6 +21,13 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
        int r = -ENOENT;
 
        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;
        }
@@ -33,6 +40,10 @@ int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
        int r = -ENOENT;
 
        switch (data->type) {
+       case KVM_XEN_ATTR_TYPE_LONG_MODE:
+               data->u.long_mode = kvm->arch.xen.long_mode;
+               r = 0;
+               break;
        default:
                break;
        }
@@ -45,6 +56,10 @@ int kvm_xen_hvm_config(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
@@ -79,7 +94,6 @@ int kvm_xen_hvm_config(struct kvm_vcpu *vcpu, u64 data)
                                return 1;
                }
        } else {
-               int lm = is_long_mode(vcpu);
                u8 *blob_addr = lm ? (u8 *)(long)kvm->arch.xen_hvm_config.blob_addr_64
                                   : (u8 *)(long)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 3d9ac2f4dc10a19a897a6acacaff7c03acc0841a..6b556ef98b767016f583837d8ce126a2ed686750 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1584,10 +1584,13 @@ struct kvm_xen_hvm_attr {
        __u16 type;
 
        union {
+               __u8 long_mode;
                __u64 pad[4];
        } u;
 };
 
+#define KVM_XEN_ATTR_TYPE_LONG_MODE            0x0
+
 /* Secure Encrypted Virtualization command */
 enum sev_cmd_id {
        /* Guest initialization commands */