KVM: x86/xen: grant table init

Add support for guest grant table initialization. This is mostly
scaffolding at this point: we allocate grant table state and map
it globally.

Later patches add support for seeding the grant table with reserved
entries, and setup maptrack which would be used for grant map and unmap
operations.

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 384247fc433d8b4e3db7a2c95c06b88f060b67a2..e0cbc08995802eb41ae17a86ac40a672cfb4bc9a 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -860,6 +860,23 @@ struct kvm_hv {
        atomic_t num_mismatched_vp_indexes;
 };
 
+/* Xen grant table */
+struct kvm_grant_table {
+       u32 nr_frames;
+       u32 max_nr_frames;
+       union {
+               void **frames;
+               struct grant_entry_v1 **frames_v1;
+       };
+       gfn_t *frames_addr;
+       gpa_t initial_addr;
+       struct grant_entry_v1 *initial;
+
+       /* maptrack limits */
+       u32 max_mt_frames;
+       u32 nr_mt_frames;
+};
+
 /* Xen emulation context */
 struct kvm_xen {
        u64 xen_hypercall;
@@ -871,6 +888,8 @@ struct kvm_xen {
        struct idr port_to_evt;
        unsigned long poll_mask[BITS_TO_LONGS(KVM_MAX_VCPUS)];
        struct mutex xen_lock;
+
+       struct kvm_grant_table gnttab;
 };
 
 enum kvm_xen_callback_via {

diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index e570c9b26563cb0c549b5cb916ee2bf09ad68924..b9e6e8f72d876512b186fee2bfc7b272ba8704b2 100644 (file)
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -17,6 +17,7 @@
 #include <xen/interface/xen.h>
 #include <xen/interface/vcpu.h>
 #include <xen/interface/event_channel.h>
+#include <xen/interface/grant_table.h>
 #include <xen/interface/sched.h>
 
 #include "trace.h"
@@ -35,6 +36,7 @@ struct evtchnfd {
 
 static int kvm_xen_evtchn_send(struct kvm_vcpu *vcpu, int port);
 static void *xen_vcpu_info(struct kvm_vcpu *v);
+static void kvm_xen_gnttab_free(struct kvm_xen *xen);
 
 #define XEN_DOMID_MIN  1
 #define XEN_DOMID_MAX  (DOMID_FIRST_RESERVED - 1)
@@ -513,6 +515,12 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
                r = kvm_xen_domid_init(kvm, any, domid);
                break;
        }
+       case KVM_XEN_ATTR_TYPE_GNTTAB: {
+               struct kvm_xen_gnttab xevfd = data->u.gnttab;
+
+               r = kvm_vm_ioctl_xen_gnttab(kvm, &xevfd);
+               break;
+       }
        default:
                break;
        }
@@ -969,6 +977,7 @@ void kvm_xen_destroy_vm(struct kvm *kvm)
                put_page(virt_to_page(xen->shinfo));
 
        kvm_xen_free_domid(kvm);
+       kvm_xen_gnttab_free(&kvm->arch.xen);
 }
 
 void kvm_xen_init(void)
@@ -1093,3 +1102,82 @@ int kvm_vm_ioctl_xen_eventfd(struct kvm *kvm, struct kvm_xen_eventfd *args)
        return kvm_xen_eventfd_assign(kvm, &xen->port_to_evt,
                                      &xen->xen_lock, args);
 }
+
+int kvm_xen_gnttab_init(struct kvm *kvm, struct kvm_xen *xen,
+                       struct kvm_xen_gnttab *op, int dom0)
+{
+       u32 max_mt_frames = op->init.max_maptrack_frames;
+       unsigned long initial = op->init.initial_frame;
+       struct kvm_grant_table *gnttab = &xen->gnttab;
+       u32 max_frames = op->init.max_frames;
+       struct page *page = NULL;
+       void *addr;
+
+       if (!dom0) {
+               if (!op->init.initial_frame ||
+                   offset_in_page(op->init.initial_frame))
+                       return -EINVAL;
+
+               if (get_user_pages_fast(initial, 1, 1, &page) != 1)
+                       return -EFAULT;
+
+               gnttab->initial_addr = initial;
+               gnttab->initial = page_to_virt(page);
+               put_page(page);
+       }
+
+       addr = kcalloc(max_frames, sizeof(gfn_t), GFP_KERNEL);
+       if (!addr)
+               goto out;
+       xen->gnttab.frames_addr = addr;
+
+       addr = kcalloc(max_frames, sizeof(addr), GFP_KERNEL);
+       if (!addr)
+               goto out;
+
+       gnttab->frames = addr;
+       gnttab->frames[0] = xen->gnttab.initial;
+       gnttab->max_nr_frames = max_frames;
+       gnttab->max_mt_frames = max_mt_frames;
+       gnttab->nr_mt_frames = 1;
+       gnttab->nr_frames = 0;
+
+       pr_debug("kvm_xen: dom%u: grant table limits (gnttab:%d maptrack:%d)\n",
+                xen->domid, gnttab->max_nr_frames, gnttab->max_mt_frames);
+       return 0;
+
+out:
+       kfree(xen->gnttab.frames);
+       kfree(xen->gnttab.frames_addr);
+       if (page)
+               put_page(page);
+       memset(&xen->gnttab, 0, sizeof(xen->gnttab));
+       return -ENOMEM;
+}
+
+void kvm_xen_gnttab_free(struct kvm_xen *xen)
+{
+       struct kvm_grant_table *gnttab = &xen->gnttab;
+
+       kfree(gnttab->frames);
+       kfree(gnttab->frames_addr);
+}
+
+int kvm_vm_ioctl_xen_gnttab(struct kvm *kvm, struct kvm_xen_gnttab *op)
+{
+       int r = -EINVAL;
+
+       if (!op)
+               return r;
+
+       switch (op->flags) {
+       case KVM_XEN_GNTTAB_F_INIT:
+               r = kvm_xen_gnttab_init(kvm, &kvm->arch.xen, op, 0);
+               break;
+       default:
+               r = -ENOSYS;
+               break;
+       }
+
+       return r;
+}

diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h
index 76ef2150c650089fddb68d041852935c0b1f2003..08ad4e1259df7e3a4e2040f88b90d7bd99b52a29 100644 (file)
--- a/arch/x86/kvm/xen.h
+++ b/arch/x86/kvm/xen.h
@@ -37,6 +37,7 @@ int kvm_xen_setup_evtchn(struct kvm *kvm,
 void kvm_xen_init_vm(struct kvm *kvm);
 void kvm_xen_destroy_vm(struct kvm *kvm);
 int kvm_vm_ioctl_xen_eventfd(struct kvm *kvm, struct kvm_xen_eventfd *args);
+int kvm_vm_ioctl_xen_gnttab(struct kvm *kvm, struct kvm_xen_gnttab *op);
 void kvm_xen_vcpu_init(struct kvm_vcpu *vcpu);
 void kvm_xen_vcpu_uninit(struct kvm_vcpu *vcpu);
 void kvm_xen_init(void);

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 3212cad732ddf6685b2935395f65a27d6fea7fa2..e4fb9bc34d61a1347f30d68273cd41637d71fdaa 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1503,6 +1503,18 @@ struct kvm_xen_hvm_attr {
                struct {
                        __s32 domid;
                } dom;
+               struct kvm_xen_gnttab {
+#define KVM_XEN_GNTTAB_F_INIT          0
+                       __u32 flags;
+                       union {
+                               struct {
+                                       __u32 max_frames;
+                                       __u32 max_maptrack_frames;
+                                       __u64 initial_frame;
+                               } init;
+                               __u32 padding[4];
+                       };
+               } gnttab;
        } u;
 };
 
@@ -1514,6 +1526,7 @@ struct kvm_xen_hvm_attr {
 /* Available with KVM_CAP_XEN_HVM_EVTCHN */
 #define KVM_XEN_ATTR_TYPE_EVTCHN            0x4
 #define KVM_XEN_ATTR_TYPE_DOMID             0x5
+#define KVM_XEN_ATTR_TYPE_GNTTAB            0x6
 
 /* Secure Encrypted Virtualization command */
 enum sev_cmd_id {