KVM: x86/xen: register shared_info page

We add a new ioctl, XEN_HVM_SHARED_INFO, to allow hypervisor
to know where the guest's shared info page is.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0f469ce439c0b3ec582961ad585b13c32c60d01d..befc0e37f16279bbbd2c194646f46728842c9ae5 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -843,6 +843,9 @@ struct kvm_hv {
 /* Xen emulation context */
 struct kvm_xen {
        u64 xen_hypercall;
+
+       gfn_t shinfo_addr;
+       struct shared_info *shinfo;
 };
 
 enum kvm_irqchip_mode {

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index be8def385e3ff00cc84fb79148742486a627bd7b..1eda9630418036d27274b549df364e2d082207da 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4793,6 +4793,26 @@ set_identity_unlock:
                r = 0;
                break;
        }
+       case KVM_XEN_HVM_GET_ATTR: {
+               struct kvm_xen_hvm_attr xha;
+
+               r = -EFAULT;
+               if (copy_from_user(&xha, argp, sizeof(xha)))
+                       goto out;
+               r = kvm_xen_hvm_get_attr(kvm, &xha);
+               if (copy_to_user(argp, &xha, sizeof(xha)))
+                       goto out;
+               break;
+       }
+       case KVM_XEN_HVM_SET_ATTR: {
+               struct kvm_xen_hvm_attr xha;
+
+               r = -EFAULT;
+               if (copy_from_user(&xha, argp, sizeof(xha)))
+                       goto out;
+               r = kvm_xen_hvm_set_attr(kvm, &xha);
+               break;
+       }
        case KVM_SET_CLOCK: {
                struct kvm_clock_data user_ns;
                u64 now_ns;
@@ -9279,6 +9299,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
        kvm_mmu_uninit_vm(kvm);
        kvm_page_track_cleanup(kvm);
        kvm_hv_destroy_vm(kvm);
+       kvm_xen_destroy_vm(kvm);
 }
 
 void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,

diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 76f0e4b812d240bfabac2e032859ecf5e8d03e09..4df223bd3cd7a3753deecde4de521e25abbfd6ef 100644 (file)
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -11,9 +11,61 @@
 #include <linux/kvm_host.h>
 
 #include <trace/events/kvm.h>
+#include <xen/interface/xen.h>
 
 #include "trace.h"
 
+static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn)
+{
+       struct shared_info *shared_info;
+       struct page *page;
+
+       page = gfn_to_page(kvm, gfn);
+       if (is_error_page(page))
+               return -EINVAL;
+
+       kvm->arch.xen.shinfo_addr = gfn;
+
+       shared_info = page_to_virt(page);
+       memset(shared_info, 0, sizeof(struct shared_info));
+       kvm->arch.xen.shinfo = shared_info;
+       return 0;
+}
+
+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_SHARED_INFO: {
+               gfn_t gfn = data->u.shared_info.gfn;
+
+               r = kvm_xen_shared_info_init(kvm, gfn);
+               break;
+       }
+       default:
+               break;
+       }
+
+       return r;
+}
+
+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_SHARED_INFO: {
+               data->u.shared_info.gfn = kvm->arch.xen.shinfo_addr;
+               break;
+       }
+       default:
+               break;
+       }
+
+       return r;
+}
+
 bool kvm_xen_hypercall_enabled(struct kvm *kvm)
 {
        return READ_ONCE(kvm->arch.xen.xen_hypercall);
@@ -77,3 +129,11 @@ int kvm_xen_hypercall(struct kvm_vcpu *vcpu)
 
        return 0;
 }
+
+void kvm_xen_destroy_vm(struct kvm *kvm)
+{
+       struct kvm_xen *xen = &kvm->arch.xen;
+
+       if (xen->shinfo)
+               put_page(virt_to_page(xen->shinfo));
+}

diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h
index a2ae079c3ef31f5ce5fa745b5205670fe55a7624..bb38edf383fe55117bb48b1ce7ba79f1db75e12e 100644 (file)
--- a/arch/x86/kvm/xen.h
+++ b/arch/x86/kvm/xen.h
@@ -3,8 +3,12 @@
 #ifndef __ARCH_X86_KVM_XEN_H__
 #define __ARCH_X86_KVM_XEN_H__
 
+int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data);
+int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data);
 bool kvm_xen_hypercall_enabled(struct kvm *kvm);
 bool kvm_xen_hypercall_set(struct kvm *kvm);
 int kvm_xen_hypercall(struct kvm_vcpu *vcpu);
 
+void kvm_xen_destroy_vm(struct kvm *kvm);
+
 #endif

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index d07520c216a12fab6133b54ae985f97bb7b25083..de2168d235af803a430a5e03784bd53c439dcfa9 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1455,6 +1455,21 @@ struct kvm_enc_region {
 /* Available with KVM_CAP_HYPERV_CPUID */
 #define KVM_GET_SUPPORTED_HV_CPUID _IOWR(KVMIO, 0xc1, struct kvm_cpuid2)
 
+#define KVM_XEN_HVM_GET_ATTR        _IOWR(KVMIO,  0xc2, struct kvm_xen_hvm_attr)
+#define KVM_XEN_HVM_SET_ATTR        _IOW(KVMIO,  0xc3, struct kvm_xen_hvm_attr)
+
+struct kvm_xen_hvm_attr {
+       __u16 type;
+
+       union {
+               struct {
+                       __u64 gfn;
+               } shared_info;
+       } u;
+};
+
+#define KVM_XEN_ATTR_TYPE_SHARED_INFO       0x0
+
 /* Secure Encrypted Virtualization command */
 enum sev_cmd_id {
        /* Guest initialization commands */