[PATCH v13 02/12] KVM: SVM: Add KVM_SEND_UPDATE_DATA command

Ashish Kalra
2021-04-15T15:54:11Z

From: Brijesh Singh <brijesh.singh@amd.com>

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>
---
.../virt/kvm/amd-memory-encryption.rst | 24 ++++
arch/x86/kvm/svm/sev.c | 122 ++++++++++++++++++
include/uapi/linux/kvm.h | 9 ++
3 files changed, 155 insertions(+)

diff --git a/Documentation/virt/kvm/amd-memory-encryption.rst b/Documentation/virt/kvm/amd-memory-encryption.rst
index ac799dd7a618..3c5456e0268a 100644
--- a/Documentation/virt/kvm/amd-memory-encryption.rst
+++ b/Documentation/virt/kvm/amd-memory-encryption.rst
@@ -311,6 +311,30 @@ Returns: 0 on success, -negative on error
__u32 session_len;
};

+11. 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.
+
+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 destition memory region */
+ __u32 trans_len;
+ };
+
References
==========

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 2b65900c05d6..30527285a39a 100644
--- 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;

@@ -1232,6 +1233,123 @@ static int sev_send_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
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);
+
+ 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;
+
+ 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;
@@ -1288,6 +1406,9 @@ 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;
@@ -1467,6 +1588,7 @@ 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 ac53ad2e7271..d45af34c31be 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1741,6 +1741,15 @@ 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)
--
2.17.1