KVM: SVM: Remove a useless zeroing of allocated memory

Remove KVM's unnecessary zeroing of memory when allocating the pages array
in sev_pin_memory() via __vmalloc(), as the array is only used to hold
kernel pointers.  The kmalloc() path for "small" regions doesn't zero the
array, and if KVM leaks state and/or accesses uninitialized data, then the
kernel has bigger problems.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/c7619a3d3cbb36463531a7c73ccbde9db587986c.1710004509.git.christophe.jaillet@wanadoo.fr
[sean: massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: tititiou36

arch/x86/kvm/svm/sev.c

@@ -434,7 +434,7 @@ static struct page **sev_pin_memory(struct kvm *kvm, unsigned long uaddr,
 	/* Avoid using vmalloc for smaller buffers. */
 	size = npages * sizeof(struct page *);
 	if (size > PAGE_SIZE)
-		pages = __vmalloc(size, GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+		pages = __vmalloc(size, GFP_KERNEL_ACCOUNT);
 	else
 		pages = kmalloc(size, GFP_KERNEL_ACCOUNT);