Re: [RFC PATCH v2 29/32] kvm: svm: Add support for SEV DEBUG_DECRYPT command
On 16/03/2017 19:41, Brijesh Singh wrote: >> >> Please do add it, it doesn't seem very different from what you're doing >> in LAUNCH_UPDATE_DATA. There's no need for a separate >> __sev_dbg_decrypt_page function, you can just pin/unpin here and do a >> per-page loop as in LAUNCH_UPDATE_DATA. > > I can certainly add support to handle crossing the page boundary cases. > Should we limit the size to prevent user passing arbitrary long length > and we end up looping inside the kernel? I was thinking to limit to a > PAGE_SIZE. I guess it depends on how it's used. PAGE_SIZE makes sense since you only know if a physical address is encrypted when you reach it from a visit of the page tables. Paolo
Re: [RFC PATCH v2 29/32] kvm: svm: Add support for SEV DEBUG_DECRYPT command
On 03/16/2017 05:54 AM, Paolo Bonzini wrote:
On 02/03/2017 16:18, Brijesh Singh wrote:
+static int __sev_dbg_decrypt_page(struct kvm *kvm, unsigned long src,
+ void *dst, int *error)
+{
+ inpages = sev_pin_memory(src, PAGE_SIZE, );
+ 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(, (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;
+
Please do add it, it doesn't seem very different from what you're doing
in LAUNCH_UPDATE_DATA. There's no need for a separate
__sev_dbg_decrypt_page function, you can just pin/unpin here and do a
per-page loop as in LAUNCH_UPDATE_DATA.
I can certainly add support to handle crossing the page boundary cases.
Should we limit the size to prevent user passing arbitrary long length
and we end up looping inside the kernel? I was thinking to limit to a PAGE_SIZE.
~ Brijesh
Re: [RFC PATCH v2 29/32] kvm: svm: Add support for SEV DEBUG_DECRYPT command
On 02/03/2017 16:18, Brijesh Singh wrote:
> +static int __sev_dbg_decrypt_page(struct kvm *kvm, unsigned long src,
> + void *dst, int *error)
> +{
> + inpages = sev_pin_memory(src, PAGE_SIZE, );
> + 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(, (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;
> +
Please do add it, it doesn't seem very different from what you're doing
in LAUNCH_UPDATE_DATA. There's no need for a separate
__sev_dbg_decrypt_page function, you can just pin/unpin here and do a
per-page loop as in LAUNCH_UPDATE_DATA.
Paolo
