From: yangge <yangge1116@xxxxxxx>
When pin_user_pages_fast() pins SEV guest memory without the
FOLL_LONGTERM flag, the pages will not get migrated out of MIGRATE_CMA/
ZONE_MOVABLE, violating these mechanisms to avoid fragmentation with
unmovable pages, for example making CMA allocations fail.
To address the aforementioned problem, we propose adding the
FOLL_LONGTERM flag to the pin_user_pages_fast() function.
Signed-off-by: yangge <yangge1116@xxxxxxx>
---
V2:
- update code and commit message suggested by David
arch/x86/kvm/svm/sev.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 943bd07..96f3b8e 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -630,6 +630,7 @@ static struct page **sev_pin_memory(struct kvm *kvm, unsigned long uaddr,
unsigned long locked, lock_limit;
struct page **pages;
unsigned long first, last;
+ unsigned int flags = FOLL_LONGTERM;
int ret;
lockdep_assert_held(&kvm->lock);
@@ -662,8 +663,10 @@ static struct page **sev_pin_memory(struct kvm *kvm, unsigned long uaddr,
if (!pages)
return ERR_PTR(-ENOMEM);
+ flags |= write ? FOLL_WRITE : 0;
+
/* Pin the user virtual address. */
- npinned = pin_user_pages_fast(uaddr, npages, write ? FOLL_WRITE : 0, pages);
+ npinned = pin_user_pages_fast(uaddr, npages, flags, pages);
if (npinned != npages) {
pr_err("SEV: Failure locking %lu pages.\n", npages);
ret = -ENOMEM;
--
2.7.4
