[RFC,Part2,18/30] KVM: SVM: add KVM_SEV_SNP_LAUNCH_UPDATE command

Commit Message

Brijesh Singh March 24, 2021, 5:04 p.m. UTC

The KVM_SEV_SNP_LAUNCH_UPDATE command can be used to insert data into the
guest's memory. The data is encrypted with the cryptographic context
created with the KVM_SEV_SNP_LAUNCH_START.

In addition to the inserting data, it can insert a two special pages
into the guests memory: the secrets page and the CPUID page.

For more information see the SEV-SNP spec section 4.5 and 8.12.

Cc: Thomas Gleixner <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Joerg Roedel <[e-mail]>
Cc: "H. Peter Anvin" <[e-mail]>
Cc: Tony Luck <[e-mail]>
Cc: Dave Hansen <[e-mail]>
Cc: "Peter Zijlstra (Intel)" <[e-mail]>
Cc: Paolo Bonzini <[e-mail]>
Cc: Tom Lendacky <[e-mail]>
Cc: David Rientjes <[e-mail]>
Cc: Sean Christopherson <[e-mail]>
Cc: Vitaly Kuznetsov <[e-mail]>
Cc: Wanpeng Li <[e-mail]>
Cc: Jim Mattson <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Brijesh Singh <[e-mail]>
---
 arch/x86/kvm/svm/sev.c   | 136 +++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/kvm.h |  18 ++++++
 2 files changed, 154 insertions(+)

Patch

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 7652e57f7e01..1a0c8c95d178 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1247,6 +1247,139 @@  static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
 	return rc;
 }
 
+static struct kvm_memory_slot *hva_to_memslot(struct kvm *kvm, unsigned long hva)
+{
+	struct kvm_memslots *slots = kvm_memslots(kvm);
+	struct kvm_memory_slot *memslot;
+
+	kvm_for_each_memslot(memslot, slots) {
+		if (hva >= memslot->userspace_addr &&
+		    hva < memslot->userspace_addr + (memslot->npages << PAGE_SHIFT))
+			return memslot;
+	}
+
+	return NULL;
+}
+
+static bool hva_to_gpa(struct kvm *kvm, unsigned long hva, gpa_t *gpa)
+{
+	struct kvm_memory_slot *memslot;
+	gpa_t gpa_offset;
+
+	memslot = hva_to_memslot(kvm, hva);
+	if (!memslot)
+		return false;
+
+	gpa_offset = hva - memslot->userspace_addr;
+	*gpa = ((memslot->base_gfn << PAGE_SHIFT) + gpa_offset);
+
+	return true;
+}
+
+static int snp_launch_update(struct kvm *kvm, struct kvm_sev_cmd *argp)
+{
+	unsigned long npages, vaddr, vaddr_end, i, next_vaddr;
+	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+	struct sev_data_snp_launch_update *data;
+	struct kvm_sev_snp_launch_update params;
+	int *error = &argp->error;
+	struct kvm_vcpu *vcpu;
+	struct page **inpages;
+	struct rmpupdate e;
+	int ret;
+
+	if (!sev_snp_guest(kvm))
+		return -ENOTTY;
+
+	if (!sev->snp_context)
+		return -EINVAL;
+
+	if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data, sizeof(params)))
+		return -EFAULT;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL_ACCOUNT);
+	if (!data)
+		return -ENOMEM;
+
+	data->gctx_paddr = __sme_page_pa(sev->snp_context);
+	data->vmpl1_perms = 0xf;
+	data->vmpl2_perms = 0xf;
+	data->vmpl3_perms = 0xf;
+
+	/* Lock the user memory. */
+	inpages = sev_pin_memory(kvm, params.uaddr, params.len, &npages, 1);
+	if (!inpages) {
+		ret = -ENOMEM;
+		goto e_free;
+	}
+
+	vcpu = kvm_get_vcpu(kvm, 0);
+	vaddr = params.uaddr;
+	vaddr_end = vaddr + params.len;
+
+	for (i = 0; vaddr < vaddr_end; vaddr = next_vaddr, i++) {
+		unsigned long psize, pmask;
+		int level = PG_LEVEL_4K;
+		gpa_t gpa;
+
+		if (!hva_to_gpa(kvm, vaddr, &gpa)) {
+			ret = -EINVAL;
+			goto e_unpin;
+		}
+
+		psize = page_level_size(level);
+		pmask = page_level_mask(level);
+		gpa = gpa & pmask;
+
+		/* Transition the page state to pre-guest */
+		memset(&e, 0, sizeof(e));
+		e.assigned = 1;
+		e.gpa = gpa;
+		e.asid = sev_get_asid(kvm);
+		e.immutable = true;
+		e.pagesize = X86_RMP_PG_LEVEL(level);
+		ret = rmptable_rmpupdate(inpages[i], &e);
+		if (ret) {
+			ret = -EFAULT;
+			goto e_unpin;
+		}
+
+		data->address = __sme_page_pa(inpages[i]);
+		data->page_size = e.pagesize;
+		data->page_type = params.page_type;
+		ret = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_LAUNCH_UPDATE, data, error);
+		if (ret) {
+			snp_page_reclaim(inpages[i], e.pagesize);
+			goto e_unpin;
+		}
+
+		next_vaddr = (vaddr & pmask) + psize;
+	}
+
+e_unpin:
+	/* Content of memory is updated, mark pages dirty */
+	memset(&e, 0, sizeof(e));
+	for (i = 0; i < npages; i++) {
+		set_page_dirty_lock(inpages[i]);
+		mark_page_accessed(inpages[i]);
+
+		/*
+		 * If its an error, then update RMP entry to change page ownership
+		 * to the hypervisor.
+		 */
+		if (ret)
+			rmptable_rmpupdate(inpages[i], &e);
+	}
+
+	/* Unlock the user pages */
+	sev_unpin_memory(kvm, inpages, npages);
+
+e_free:
+	kfree(data);
+
+	return ret;
+}
+
 int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
 {
 	struct kvm_sev_cmd sev_cmd;
@@ -1303,6 +1436,9 @@  int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
 	case KVM_SEV_SNP_LAUNCH_START:
 		r = snp_launch_start(kvm, &sev_cmd);
 		break;
+	case KVM_SEV_SNP_LAUNCH_UPDATE:
+		r = snp_launch_update(kvm, &sev_cmd);
+		break;
 	default:
 		r = -EINVAL;
 		goto out;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 84a242597d81..a9f7aa9e412d 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1597,6 +1597,7 @@  enum sev_cmd_id {
 	/* SNP specific commands */
 	KVM_SEV_SNP_INIT,
 	KVM_SEV_SNP_LAUNCH_START,
+	KVM_SEV_SNP_LAUNCH_UPDATE,
 
 	KVM_SEV_NR_MAX,
 };
@@ -1656,6 +1657,23 @@  struct kvm_sev_snp_launch_start {
 	__u8 imi_en;
 };
 
+#define KVM_SEV_SNP_PAGE_TYPE_NORMAL		0x1
+#define KVM_SEV_SNP_PAGE_TYPE_VMSA		0x2
+#define KVM_SEV_SNP_PAGE_TYPE_ZERO		0x3
+#define KVM_SEV_SNP_PAGE_TYPE_UNMEASURED	0x4
+#define KVM_SEV_SNP_PAGE_TYPE_SECRETS		0x5
+#define KVM_SEV_SNP_PAGE_TYPE_CPUID		0x6
+
+struct kvm_sev_snp_launch_update {
+	__u64 uaddr;
+	__u32 len;
+	__u8 imi_page;
+	__u8 page_type;
+	__u8 vmpl3_perms;
+	__u8 vmpl2_perms;
+	__u8 vmpl1_perms;
+};
+
 #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)