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>

1 files changed, 125 insertions, 0 deletions

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 9f5312956d5e..a534ec9ae172 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;
 
@@ -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);