On 07/04/21 00:49, Sean Christopherson wrote:
For commands with small input/output buffers, use the local stack to
"allocate" the structures used to communicate with the PSP.   Now that
__sev_do_cmd_locked() gracefully handles vmalloc'd buffers, there's no
reason to avoid using the stack, e.g. CONFIG_VMAP_STACK=y will just work.

Signed-off-by: Sean Christopherson <sea...@google.com>

Squashing this in (inspired by Christophe's review, though not quite
matching his suggestion).

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 0f5644a3b138..246b281b6376 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -408,12 +408,11 @@ static int sev_ioctl_do_pek_csr(struct sev_issue_cmd 
*argp, bool writable)
        if (copy_from_user(&input, (void __user *)argp->data, sizeof(input)))
                return -EFAULT;
+ memset(&data, 0, sizeof(data));
        /* userspace wants to query CSR length */
-       if (!input.address || !input.length) {
-               data.address = 0;
-               data.len = 0;
+       if (!input.address || !input.length)
                goto cmd;
-       }
/* allocate a physically contiguous buffer to store the CSR blob */
        input_address = (void __user *)input.address;

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