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[PATCH] util/vfio-helpers.c: Use ram_block_discard_disable() in qemu_vfi
From: |
David Hildenbrand |
Subject: |
[PATCH] util/vfio-helpers.c: Use ram_block_discard_disable() in qemu_vfio_open_pci() |
Date: |
Mon, 16 Nov 2020 11:59:47 +0100 |
Currently, when using "nvme://" for a block device, like
-drive file=nvme://0000:01:00.0/1,if=none,id=drive0 \
-device virtio-blk,drive=drive0 \
VFIO may pin all guest memory, and discarding of RAM no longer works as
expected. I was able to reproduce this easily with my
01:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd
NVMe SSD Controller SM981/PM981/PM983
Similar to common VFIO, we have to disable it, making sure that:
a) virtio-balloon won't discard any memory ("silently disabled")
b) virtio-mem and nvme:// run mutually exclusive
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
stubs/ram-block.c | 6 ++++++
util/vfio-helpers.c | 14 ++++++++++++++
2 files changed, 20 insertions(+)
diff --git a/stubs/ram-block.c b/stubs/ram-block.c
index 73c0a3ee08..108197683b 100644
--- a/stubs/ram-block.c
+++ b/stubs/ram-block.c
@@ -1,6 +1,7 @@
#include "qemu/osdep.h"
#include "exec/ramlist.h"
#include "exec/cpu-common.h"
+#include "exec/memory.h"
void *qemu_ram_get_host_addr(RAMBlock *rb)
{
@@ -29,3 +30,8 @@ int qemu_ram_foreach_block(RAMBlockIterFunc func, void
*opaque)
{
return 0;
}
+
+int ram_block_discard_disable(bool state)
+{
+ return 0;
+}
diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c
index c469beb061..2bec48e163 100644
--- a/util/vfio-helpers.c
+++ b/util/vfio-helpers.c
@@ -16,6 +16,7 @@
#include "qapi/error.h"
#include "exec/ramlist.h"
#include "exec/cpu-common.h"
+#include "exec/memory.h"
#include "trace.h"
#include "qemu/error-report.h"
#include "standard-headers/linux/pci_regs.h"
@@ -494,8 +495,20 @@ QEMUVFIOState *qemu_vfio_open_pci(const char *device,
Error **errp)
int r;
QEMUVFIOState *s = g_new0(QEMUVFIOState, 1);
+ /*
+ * VFIO may pin all memory inside mappings, resulting it in pinning
+ * all memory inside RAM blocks unconditionally.
+ */
+ r = ram_block_discard_disable(true);
+ if (r) {
+ error_setg_errno(errp, -r, "Cannot set discarding of RAM broken");
+ g_free(s);
+ return NULL;
+ }
+
r = qemu_vfio_init_pci(s, device, errp);
if (r) {
+ ram_block_discard_disable(false);
g_free(s);
return NULL;
}
@@ -837,4 +850,5 @@ void qemu_vfio_close(QEMUVFIOState *s)
close(s->device);
close(s->group);
close(s->container);
+ ram_block_discard_disable(false);
}
--
2.26.2
- [PATCH] util/vfio-helpers.c: Use ram_block_discard_disable() in qemu_vfio_open_pci(),
David Hildenbrand <=