[PATCH] KVM: x86: report sev_pin_memory errors with PTR_ERR

[Paolo Bonzini]

Callers of sev_pin_memory() treat
NULL differently:

sev_launch_secret()/svm_register_enc_region() return -ENOMEM
sev_dbg_crypt() returns -EFAULT.

Switching to ERR_PTR() preserves the error and enables cleaner reporting of
different kinds of failures.

Suggested-by: Vitaly Kuznetsov <vkuzn...@redhat.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
 arch/x86/kvm/svm/sev.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index a893624b9275..2b4916ffa906 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -320,7 +320,7 @@ static struct page **sev_pin_memory(struct kvm *kvm, 
unsigned long uaddr,
        unsigned long first, last;
 
        if (ulen == 0 || uaddr + ulen < uaddr)
-               return NULL;
+               return ERR_PTR(-EINVAL);
 
        /* Calculate number of pages. */
        first = (uaddr & PAGE_MASK) >> PAGE_SHIFT;
@@ -331,11 +331,11 @@ static struct page **sev_pin_memory(struct kvm *kvm, 
unsigned long uaddr,
        lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
        if (locked > lock_limit && !capable(CAP_IPC_LOCK)) {
                pr_err("SEV: %lu locked pages exceed the lock limit of %lu.\n", 
locked, lock_limit);
-               return NULL;
+               return ERR_PTR(-ENOMEM);
        }
 
        if (WARN_ON_ONCE(npages > INT_MAX))
-               return NULL;
+               return ERR_PTR(-EINVAL);
 
        /* Avoid using vmalloc for smaller buffers. */
        size = npages * sizeof(struct page *);
@@ -345,7 +345,7 @@ static struct page **sev_pin_memory(struct kvm *kvm, 
unsigned long uaddr,
                pages = kmalloc(size, GFP_KERNEL_ACCOUNT);
 
        if (!pages)
-               return NULL;
+               return ERR_PTR(-ENOMEM);
 
        /* Pin the user virtual address. */
        npinned = pin_user_pages_fast(uaddr, npages, write ? FOLL_WRITE : 0, 
pages);
@@ -360,11 +360,13 @@ static struct page **sev_pin_memory(struct kvm *kvm, 
unsigned long uaddr,
        return pages;
 
 err:
-       if (npinned > 0)
+       if (npinned > 0) {
                unpin_user_pages(pages, npinned);
+               npinned = -ENOMEM;
+       }
 
        kvfree(pages);
-       return NULL;
+       return ERR_PTR(npinned);
 }
 
 static void sev_unpin_memory(struct kvm *kvm, struct page **pages,
@@ -864,8 +866,8 @@ static int sev_launch_secret(struct kvm *kvm, struct 
kvm_sev_cmd *argp)
                return -EFAULT;
 
        pages = sev_pin_memory(kvm, params.guest_uaddr, params.guest_len, &n, 
1);
-       if (!pages)
-               return -ENOMEM;
+       if (IS_ERR(pages))
+               return PTR_ERR(pages);
 
        /*
         * The secret must be copied into contiguous memory region, lets verify
@@ -991,8 +993,8 @@ int svm_register_enc_region(struct kvm *kvm,
                return -ENOMEM;
 
        region->pages = sev_pin_memory(kvm, range->addr, range->size, 
&region->npages, 1);
-       if (!region->pages) {
-               ret = -ENOMEM;
+       if (IS_ERR(region->pages)) {
+               ret = PTR_ERR(region->pages);
                goto e_free;
        }
 
-- 
2.26.2