On Tue, Jan 26, 2021, Tom Lendacky wrote:

On 1/26/21 12:54 PM, Peter Gonda wrote:

quoted

sev_pin_memory assumes that callers hold the kvm->lock. This was true for
all callers except svm_register_enc_region since it does not originate
from svm_mem_enc_op. Also added lockdep annotation to help prevent
future regressions.

I'm not exactly sure what the problem is that your fixing? What is the
symptom that you're seeing?

svm_register_enc_region() calls sev_pin_memory() without holding kvm->lock.  If
userspace does multiple KVM_MEMORY_ENCRYPT_REG_REGION in parallel, it could
circumvent the rlimit(RLIMIT_MEMLOCK) check.