The command is used to decrypt guest memory region for debug purposes.
Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
---
arch/x86/kvm/svm.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 76 insertions(+)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 977aa22..ce8819a 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5986,6 +5986,78 @@ static int sev_guest_status(struct kvm *kvm, struct kvm_sev_cmd *argp)
return ret;
}
+static int __sev_dbg_decrypt_page(struct kvm *kvm, unsigned long src,
+ void *dst, int *error)
+{
+ int ret;
+ struct page **inpages;
+ struct sev_data_dbg *data;
+ unsigned long npages;
+
+ data = kzalloc(sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ inpages = sev_pin_memory(src, PAGE_SIZE, &npages);
+ if (!inpages) {
+ ret = -ENOMEM;
+ goto err_1;
+ }
+
+ data->handle = sev_get_handle(kvm);
+ data->dst_addr = __psp_pa(dst);
+ data->src_addr = __sev_page_pa(inpages[0]);
+ data->length = PAGE_SIZE;
+
+ ret = sev_issue_cmd(kvm, SEV_CMD_DBG_DECRYPT, data, error);
+ if (ret)
+ printk(KERN_ERR "SEV: DEBUG_DECRYPT %d (%#010x)\n",
+ ret, *error);
+ sev_unpin_memory(inpages, npages);
+err_1:
+ kfree(data);
+ return ret;
+}
+
+static int sev_dbg_decrypt(struct kvm *kvm, struct kvm_sev_cmd *argp)
+{
+ void *data;
+ int ret, offset, len;
+ struct kvm_sev_dbg debug;
+
+ if (!sev_guest(kvm))
+ return -ENOTTY;
+
+ if (copy_from_user(&debug, (void *)argp->data,
+ sizeof(struct kvm_sev_dbg)))
+ return -EFAULT;
+ /*
+ * TODO: add support for decrypting length which crosses the
+ * page boundary.
+ */
+ offset = debug.src_addr & (PAGE_SIZE - 1);
+ if (offset + debug.length > PAGE_SIZE)
+ return -EINVAL;
+
+ data = (void *) get_zeroed_page(GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ /* decrypt full page */
+ ret = __sev_dbg_decrypt_page(kvm, debug.src_addr & PAGE_MASK,
+ data, &argp->error);
+ if (ret)
+ goto err_1;
+
+ /* we have decrypted full page but copy request length */
+ len = min_t(size_t, (PAGE_SIZE - offset), debug.length);
+ if (copy_to_user((uint8_t *)debug.dst_addr, data + offset, len))
+ ret = -EFAULT;
+err_1:
+ free_page((unsigned long)data);
+ return ret;
+}
+
static int amd_memory_encryption_cmd(struct kvm *kvm, void __user *argp)
{
int r = -ENOTTY;
@@ -6013,6 +6085,10 @@ static int amd_memory_encryption_cmd(struct kvm *kvm, void __user *argp)
r = sev_guest_status(kvm, &sev_cmd);
break;
}
+ case KVM_SEV_DBG_DECRYPT: {
+ r = sev_dbg_decrypt(kvm, &sev_cmd);
+ break;
+ }
default:
break;
}
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
