From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org,
David Hildenbrand <david@redhat.com>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Sven Schnelle <svens@linux.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
Matthew Wilcox <willy@infradead.org>,
Thomas Huth <thuth@redhat.com>
Subject: [PATCH v2 02/10] s390/uv: gmap_make_secure() cleanups for further changes
Date: Fri, 12 Apr 2024 16:21:12 +0200 [thread overview]
Message-ID: <20240412142120.220087-3-david@redhat.com> (raw)
In-Reply-To: <20240412142120.220087-1-david@redhat.com>
Let's factor out handling of LRU cache draining and convert the if-else
chain to a switch-case.
Signed-off-by: David Hildenbrand <david@redhat.com>
---
arch/s390/kernel/uv.c | 66 ++++++++++++++++++++++++++-----------------
1 file changed, 40 insertions(+), 26 deletions(-)
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index 016993e9eb72..25fe28d189df 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -266,6 +266,36 @@ static bool should_export_before_import(struct uv_cb_header *uvcb, struct mm_str
return atomic_read(&mm->context.protected_count) > 1;
}
+/*
+ * Drain LRU caches: the local one on first invocation and the ones of all
+ * CPUs on successive invocations. Returns "true" on the first invocation.
+ */
+static bool drain_lru(bool *drain_lru_called)
+{
+ /*
+ * If we have tried a local drain and the folio refcount
+ * still does not match our expected safe value, try with a
+ * system wide drain. This is needed if the pagevecs holding
+ * the page are on a different CPU.
+ */
+ if (*drain_lru_called) {
+ lru_add_drain_all();
+ /* We give up here, don't retry immediately. */
+ return false;
+ }
+ /*
+ * We are here if the folio refcount does not match the
+ * expected safe value. The main culprits are usually
+ * pagevecs. With lru_add_drain() we drain the pagevecs
+ * on the local CPU so that hopefully the refcount will
+ * reach the expected safe value.
+ */
+ lru_add_drain();
+ *drain_lru_called = true;
+ /* The caller should try again immediately */
+ return true;
+}
+
/*
* Requests the Ultravisor to make a page accessible to a guest.
* If it's brought in the first time, it will be cleared. If
@@ -275,7 +305,7 @@ static bool should_export_before_import(struct uv_cb_header *uvcb, struct mm_str
int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb)
{
struct vm_area_struct *vma;
- bool local_drain = false;
+ bool drain_lru_called = false;
spinlock_t *ptelock;
unsigned long uaddr;
struct folio *folio;
@@ -331,37 +361,21 @@ int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb)
out:
mmap_read_unlock(gmap->mm);
- if (rc == -EAGAIN) {
+ switch (rc) {
+ case -EAGAIN:
/*
* If we are here because the UVC returned busy or partial
* completion, this is just a useless check, but it is safe.
*/
folio_wait_writeback(folio);
folio_put(folio);
- } else if (rc == -EBUSY) {
- /*
- * If we have tried a local drain and the folio refcount
- * still does not match our expected safe value, try with a
- * system wide drain. This is needed if the pagevecs holding
- * the page are on a different CPU.
- */
- if (local_drain) {
- lru_add_drain_all();
- /* We give up here, and let the caller try again */
- return -EAGAIN;
- }
- /*
- * We are here if the folio refcount does not match the
- * expected safe value. The main culprits are usually
- * pagevecs. With lru_add_drain() we drain the pagevecs
- * on the local CPU so that hopefully the refcount will
- * reach the expected safe value.
- */
- lru_add_drain();
- local_drain = true;
- /* And now we try again immediately after draining */
- goto again;
- } else if (rc == -ENXIO) {
+ return -EAGAIN;
+ case -EBUSY:
+ /* Additional folio references. */
+ if (drain_lru(&drain_lru_called))
+ goto again;
+ return -EAGAIN;
+ case -ENXIO:
if (gmap_fault(gmap, gaddr, FAULT_FLAG_WRITE))
return -EFAULT;
return -EAGAIN;
--
2.44.0
next prev parent reply other threads:[~2024-04-12 14:21 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-12 14:21 [PATCH v2 00/10] s390: PG_arch_1+folio cleanups for uv+hugetlb David Hildenbrand
2024-04-12 14:21 ` [PATCH v2 01/10] s390/uv: don't call folio_wait_writeback() without a folio reference David Hildenbrand
2024-04-12 14:21 ` David Hildenbrand [this message]
2024-05-07 15:27 ` [PATCH v2 02/10] s390/uv: gmap_make_secure() cleanups for further changes Claudio Imbrenda
2024-04-12 14:21 ` [PATCH v2 03/10] s390/uv: split large folios in gmap_make_secure() David Hildenbrand
2024-05-07 15:43 ` Claudio Imbrenda
2024-04-12 14:21 ` [PATCH v2 04/10] s390/uv: convert PG_arch_1 users to only work on small folios David Hildenbrand
2024-05-07 15:49 ` Claudio Imbrenda
2024-04-12 14:21 ` [PATCH v2 05/10] s390/uv: update PG_arch_1 comment David Hildenbrand
2024-04-12 14:21 ` [PATCH v2 06/10] s390/uv: make uv_convert_from_secure() a static function David Hildenbrand
2024-05-07 15:53 ` Claudio Imbrenda
2024-04-12 14:21 ` [PATCH v2 07/10] s390/uv: convert uv_destroy_owned_page() to uv_destroy_(folio|pte)() David Hildenbrand
2024-05-07 16:25 ` Claudio Imbrenda
2024-04-12 14:21 ` [PATCH v2 08/10] s390/uv: convert uv_convert_owned_from_secure() to uv_convert_from_secure_(folio|pte)() David Hildenbrand
2024-05-07 16:26 ` Claudio Imbrenda
2024-04-12 14:21 ` [PATCH v2 09/10] s390/uv: implement HAVE_ARCH_MAKE_FOLIO_ACCESSIBLE David Hildenbrand
2024-05-07 16:29 ` Claudio Imbrenda
2024-04-12 14:21 ` [PATCH v2 10/10] s390/hugetlb: convert PG_arch_1 code to work on folio->flags David Hildenbrand
2024-05-07 16:33 ` Claudio Imbrenda
2024-05-08 18:08 ` David Hildenbrand
2024-05-10 8:45 ` Claudio Imbrenda
2024-04-30 18:49 ` [PATCH v2 00/10] s390: PG_arch_1+folio cleanups for uv+hugetlb David Hildenbrand
2024-05-06 8:38 ` Heiko Carstens
2024-05-07 16:34 ` Claudio Imbrenda
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