KVM: SVM: Add KVM_SEND_UPDATE_DATA command

The command is used for encrypting the guest memory region using the encryption
context created with KVM_SEV_SEND_START.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: x86@kernel.org
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by : Steve Rutherford <srutherford@google.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Message-Id: <d6a6ea740b0c668b30905ae31eac5ad7da048bb3.1618498113.git.ashish.kalra@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/Documentation/virt/kvm/amd-memory-encryption.rst b/Documentation/virt/kvm/amd-memory-encryption.rst
index db5c3fb2bab5a1adab1774ecbd7f7285c62d297e..79da88a141355a22160ad4d0b367d9cc570f8996 100644 (file)
--- a/Documentation/virt/kvm/amd-memory-encryption.rst
+++ b/Documentation/virt/kvm/amd-memory-encryption.rst
@@ -320,6 +320,34 @@ Returns: 0 on success, -negative on error
                 __u32 session_len;
         };
 
+12. KVM_SEV_SEND_UPDATE_DATA
+----------------------------
+
+The KVM_SEV_SEND_UPDATE_DATA command can be used by the hypervisor to encrypt the
+outgoing guest memory region with the encryption context creating using
+KVM_SEV_SEND_START.
+
+If hdr_len or trans_len are zero on entry, the length of the packet header and
+transport region are written to hdr_len and trans_len respectively, and all
+other fields are not used.
+
+Parameters (in): struct kvm_sev_send_update_data
+
+Returns: 0 on success, -negative on error
+
+::
+
+        struct kvm_sev_launch_send_update_data {
+                __u64 hdr_uaddr;        /* userspace address containing the packet header */
+                __u32 hdr_len;
+
+                __u64 guest_uaddr;      /* the source memory region to be encrypted */
+                __u32 guest_len;
+
+                __u64 trans_uaddr;      /* the destination memory region  */
+                __u32 trans_len;
+        };
+
 References
 ==========
 

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 9f5312956d5e2b252cc6fc0e64d6f174d7357dc2..a534ec9ae172c2ebe1884672e0934c82e90f84a1 100644 (file)
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -34,6 +34,7 @@ static DECLARE_RWSEM(sev_deactivate_lock);
 static DEFINE_MUTEX(sev_bitmap_lock);
 unsigned int max_sev_asid;
 static unsigned int min_sev_asid;
+static unsigned long sev_me_mask;
 static unsigned long *sev_asid_bitmap;
 static unsigned long *sev_reclaim_asid_bitmap;
 
@@ -1236,6 +1237,126 @@ e_free_session:
        return ret;
 }
 
+/* Userspace wants to query either header or trans length. */
+static int
+__sev_send_update_data_query_lengths(struct kvm *kvm, struct kvm_sev_cmd *argp,
+                                    struct kvm_sev_send_update_data *params)
+{
+       struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+       struct sev_data_send_update_data *data;
+       int ret;
+
+       data = kzalloc(sizeof(*data), GFP_KERNEL_ACCOUNT);
+       if (!data)
+               return -ENOMEM;
+
+       data->handle = sev->handle;
+       ret = sev_issue_cmd(kvm, SEV_CMD_SEND_UPDATE_DATA, data, &argp->error);
+       if (ret < 0)
+               goto out;
+
+       params->hdr_len = data->hdr_len;
+       params->trans_len = data->trans_len;
+
+       if (copy_to_user((void __user *)(uintptr_t)argp->data, params,
+                        sizeof(struct kvm_sev_send_update_data)))
+               ret = -EFAULT;
+
+out:
+       kfree(data);
+       return ret;
+}
+
+static int sev_send_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
+{
+       struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+       struct sev_data_send_update_data *data;
+       struct kvm_sev_send_update_data params;
+       void *hdr, *trans_data;
+       struct page **guest_page;
+       unsigned long n;
+       int ret, offset;
+
+       if (!sev_guest(kvm))
+               return -ENOTTY;
+
+       if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data,
+                       sizeof(struct kvm_sev_send_update_data)))
+               return -EFAULT;
+
+       /* userspace wants to query either header or trans length */
+       if (!params.trans_len || !params.hdr_len)
+               return __sev_send_update_data_query_lengths(kvm, argp, &params);
+
+       if (!params.trans_uaddr || !params.guest_uaddr ||
+           !params.guest_len || !params.hdr_uaddr)
+               return -EINVAL;
+
+       /* Check if we are crossing the page boundary */
+       offset = params.guest_uaddr & (PAGE_SIZE - 1);
+       if ((params.guest_len + offset > PAGE_SIZE))
+               return -EINVAL;
+
+       /* Pin guest memory */
+       guest_page = sev_pin_memory(kvm, params.guest_uaddr & PAGE_MASK,
+                                   PAGE_SIZE, &n, 0);
+       if (!guest_page)
+               return -EFAULT;
+
+       /* allocate memory for header and transport buffer */
+       ret = -ENOMEM;
+       hdr = kmalloc(params.hdr_len, GFP_KERNEL_ACCOUNT);
+       if (!hdr)
+               goto e_unpin;
+
+       trans_data = kmalloc(params.trans_len, GFP_KERNEL_ACCOUNT);
+       if (!trans_data)
+               goto e_free_hdr;
+
+       data = kzalloc(sizeof(*data), GFP_KERNEL);
+       if (!data)
+               goto e_free_trans_data;
+
+       data->hdr_address = __psp_pa(hdr);
+       data->hdr_len = params.hdr_len;
+       data->trans_address = __psp_pa(trans_data);
+       data->trans_len = params.trans_len;
+
+       /* The SEND_UPDATE_DATA command requires C-bit to be always set. */
+       data->guest_address = (page_to_pfn(guest_page[0]) << PAGE_SHIFT) +
+                               offset;
+       data->guest_address |= sev_me_mask;
+       data->guest_len = params.guest_len;
+       data->handle = sev->handle;
+
+       ret = sev_issue_cmd(kvm, SEV_CMD_SEND_UPDATE_DATA, data, &argp->error);
+
+       if (ret)
+               goto e_free;
+
+       /* copy transport buffer to user space */
+       if (copy_to_user((void __user *)(uintptr_t)params.trans_uaddr,
+                        trans_data, params.trans_len)) {
+               ret = -EFAULT;
+               goto e_free;
+       }
+
+       /* Copy packet header to userspace. */
+       ret = copy_to_user((void __user *)(uintptr_t)params.hdr_uaddr, hdr,
+                               params.hdr_len);
+
+e_free:
+       kfree(data);
+e_free_trans_data:
+       kfree(trans_data);
+e_free_hdr:
+       kfree(hdr);
+e_unpin:
+       sev_unpin_memory(kvm, guest_page, n);
+
+       return ret;
+}
+
 int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
 {
        struct kvm_sev_cmd sev_cmd;
@@ -1301,6 +1422,9 @@ int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
        case KVM_SEV_SEND_START:
                r = sev_send_start(kvm, &sev_cmd);
                break;
+       case KVM_SEV_SEND_UPDATE_DATA:
+               r = sev_send_update_data(kvm, &sev_cmd);
+               break;
        default:
                r = -EINVAL;
                goto out;
@@ -1559,6 +1683,7 @@ void __init sev_hardware_setup(void)
 
        /* Minimum ASID value that should be used for SEV guest */
        min_sev_asid = edx;
+       sev_me_mask = 1UL << (ebx & 0x3f);
 
        /* Initialize SEV ASID bitmaps */
        sev_asid_bitmap = bitmap_zalloc(max_sev_asid, GFP_KERNEL);

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 11b3e528d35d8e95faf671fe7ecf8699317bd266..d07be69f402f45f0958d411abee77df05520fdd8 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1744,6 +1744,15 @@ struct kvm_sev_send_start {
        __u32 session_len;
 };
 
+struct kvm_sev_send_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)