[Qemu-devel] [RFC PATCH v1 05/10] KVM: SVM: Add KVM_SEV_RECEIVE_UPDATE_DATA command

[Singh, Brijesh]

The command is used for copying the incoming buffer into the
SEV guest memory space.

Cc: Thomas Gleixner <address@hidden>
Cc: Ingo Molnar <address@hidden>
Cc: "H. Peter Anvin" <address@hidden>
Cc: Paolo Bonzini <address@hidden>
Cc: "Radim Krčmář" <address@hidden>
Cc: Joerg Roedel <address@hidden>
Cc: Borislav Petkov <address@hidden>
Cc: Tom Lendacky <address@hidden>
Cc: address@hidden
Cc: address@hidden
Cc: address@hidden
Signed-off-by: Brijesh Singh <address@hidden>
---
 .../virtual/kvm/amd-memory-encryption.rst     | 24 ++++++
 arch/x86/kvm/svm.c                            | 84 +++++++++++++++++++
 include/uapi/linux/kvm.h                      |  9 ++
 3 files changed, 117 insertions(+)

diff --git a/Documentation/virtual/kvm/amd-memory-encryption.rst 
b/Documentation/virtual/kvm/amd-memory-encryption.rst
index acdff2454649..b9c3dc02f344 100644
--- a/Documentation/virtual/kvm/amd-memory-encryption.rst
+++ b/Documentation/virtual/kvm/amd-memory-encryption.rst
@@ -322,6 +322,30 @@ On success, the 'handle' field contains a new handle and 
on error, a negative va
 
 For more details, see SEV spec Section 6.12.
 
+14. KVM_SEV_RECEIVE_UPDATE_DATA
+----------------------------
+
+The KVM_SEV_RECEIVE_UPDATE_DATA command can be used by the hypervisor to copy
+the incoming buffers into the guest memory region with encryption context
+created during the KVM_SEV_RECEIVE_START.
+
+Parameters (in): struct kvm_sev_receive_update_data
+
+Returns: 0 on success, -negative on error
+
+::
+
+        struct kvm_sev_launch_receive_update_data {
+                __u64 hdr_uaddr;        /* userspace address containing the 
packet header */
+                __u32 hdr_len;
+
+                __u64 guest_uaddr;      /* the destination guest memory region 
*/
+                __u32 guest_len;
+
+                __u64 trans_uaddr;      /* the incoming buffer memory region  
*/
+                __u32 trans_len;
+        };
+
 References
 ==========
 
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index a7dcf19baefb..c81cac09c5af 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -7269,6 +7269,87 @@ static int sev_receive_start(struct kvm *kvm, struct 
kvm_sev_cmd *argp)
        return ret;
 }
 
+static int sev_receive_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
+{
+       struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+       struct kvm_sev_receive_update_data params;
+       struct sev_data_receive_update_data *data;
+       void *hdr = NULL, *trans = NULL;
+       struct page **guest_page;
+       unsigned long n;
+       int ret, offset;
+
+       if (!sev_guest(kvm))
+               return -EINVAL;
+
+       if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data,
+                       sizeof(struct kvm_sev_receive_update_data)))
+               return -EFAULT;
+
+       if (!params.hdr_uaddr || !params.hdr_len ||
+           !params.guest_uaddr || !params.guest_len ||
+           !params.trans_uaddr || !params.trans_len)
+               return -EINVAL;
+
+       /* Check if we are crossing the page boundry */
+       offset = params.guest_uaddr & (PAGE_SIZE - 1);
+       if ((params.guest_len + offset > PAGE_SIZE))
+               return -EINVAL;
+
+       data = kzalloc(sizeof(*data), GFP_KERNEL);
+       if (!data)
+               return -ENOMEM;
+
+       hdr = psp_copy_user_blob(params.hdr_uaddr, params.hdr_len);
+       if (IS_ERR(hdr)) {
+               ret = PTR_ERR(hdr);
+               goto e_free;
+       }
+
+       data->hdr_address = __psp_pa(hdr);
+       data->hdr_len = params.hdr_len;
+
+       trans = psp_copy_user_blob(params.trans_uaddr, params.trans_len);
+       if (IS_ERR(trans)) {
+               ret = PTR_ERR(trans);
+               goto e_free;
+       }
+
+       data->trans_address = __psp_pa(trans);
+       data->trans_len = params.trans_len;
+
+       /* Pin guest memory */
+       ret = -EFAULT;
+       guest_page = sev_pin_memory(kvm, params.guest_uaddr & PAGE_MASK,
+                                   PAGE_SIZE, &n, 0);
+       if (!guest_page)
+               goto e_free;
+
+       data->guest_address = __sme_page_pa(guest_page[0]) + offset;
+       data->guest_len = params.guest_len;
+
+       /*
+        * The RECEIVE_UPDATE_DATA command requires C-bit to be always set.
+        * The __sme_page_pa() takes care of setting the C-bit only when SME
+        * is enabled on the host. But we need to set the C-bit regarless of
+        * the SME state.
+        */
+       data->guest_address |= me_mask;
+
+       /* flush the caches to ensure that DRAM has recent contents */
+       sev_clflush_pages(guest_page, n);
+
+       data->handle = sev->handle;
+       ret = sev_issue_cmd(kvm, SEV_CMD_RECEIVE_UPDATE_DATA, data, 
&argp->error);
+
+       sev_unpin_memory(kvm, guest_page, n);
+e_free:
+       kfree(data);
+       kfree(hdr);
+       kfree(trans);
+       return ret;
+}
+
 static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
 {
        struct kvm_sev_cmd sev_cmd;
@@ -7322,6 +7403,9 @@ static int svm_mem_enc_op(struct kvm *kvm, void __user 
*argp)
        case KVM_SEV_RECEIVE_START:
                r = sev_receive_start(kvm, &sev_cmd);
                break;
+       case KVM_SEV_RECEIVE_UPDATE_DATA:
+               r = sev_receive_update_data(kvm, &sev_cmd);
+               break;
        default:
                r = -EINVAL;
                goto out;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index fee75bf1fd90..07e058a3ec11 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1550,6 +1550,15 @@ struct kvm_sev_receive_start {
        __u32 session_len;
 };
 
+struct kvm_sev_receive_update_data {
+       __u64 hdr_uaddr;
+       __u32 hdr_len;
+       __u64 guest_uaddr;
+       __u32 guest_len;
+       __u64 trans_uaddr;
+       __u32 trans_len;
+};
+
 #define KVM_DEV_ASSIGN_ENABLE_IOMMU    (1 << 0)
 #define KVM_DEV_ASSIGN_PCI_2_3         (1 << 1)
 #define KVM_DEV_ASSIGN_MASK_INTX       (1 << 2)
-- 
2.17.1