From: Nitesh Narayan Lal <nilal@xxxxxxxxxx>
This patch enables QEMU to handle page hinting requests
from the guest. Once the guest kicks QEMU to free a page,
QEMU retrives the guest physical address and converts it to
host virtual address and then MADVISE that memory.
Signed-off-by: Nitesh Narayan Lal <nilal@xxxxxxxxxx>
---
hw/virtio/virtio-balloon.c | 54 ++++++++++++++++++++++++++++++++++++++
hw/virtio/virtio.c | 24 +++++++++++++++++
include/hw/virtio/virtio-access.h | 1 +
include/hw/virtio/virtio-balloon.h | 2 +-
include/qemu/osdep.h | 7 +++++
5 files changed, 87 insertions(+), 1 deletion(-)
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 37cde38..a0e3c41 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -33,6 +33,8 @@
#define BALLOON_PAGE_SIZE (1 << VIRTIO_BALLOON_PFN_SHIFT)
+void page_hinting_request(uint64_t addr, uint32_t len);
+
static void balloon_page(void *addr, int deflate)
{
if (!qemu_balloon_is_inhibited() && (!kvm_enabled() ||
@@ -205,6 +207,57 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
balloon_stats_change_timer(s, 0);
}
+static void *gpa2hva(MemoryRegion **p_mr, hwaddr addr, Error **errp)
+{
+ MemoryRegionSection mrs = memory_region_find(get_system_memory(),
+ addr, 1);
+
+ if (!mrs.mr) {
+ error_setg(errp, "No memory is mapped at address 0x%" HWADDR_PRIx, addr);
+ return NULL;
+ }
+
+ if (!memory_region_is_ram(mrs.mr) && !memory_region_is_romd(mrs.mr)) {
+ error_setg(errp, "Memory at address 0x%" HWADDR_PRIx "is not RAM", addr);
+ memory_region_unref(mrs.mr);
+ return NULL;
+ }
+
+ *p_mr = mrs.mr;
+ return qemu_map_ram_ptr(mrs.mr->ram_block, mrs.offset_within_region);
+}
+
+void page_hinting_request(uint64_t addr, uint32_t len)
+{
+ Error *local_err = NULL;
+ MemoryRegion *mr = NULL;
+ void *ptr;
+ int ret = 0;
+
+ /*ptr is the host physical address*/
+ ptr = gpa2hva(&mr, addr, &local_err);
+ if (local_err) {
+ error_report_err(local_err);
+ return;
+ }
+ ret = qemu_madvise((void *)ptr, len, QEMU_MADV_FREE);
+ if (ret == -1)
+ printf("\n%d:%s Error: Madvise failed with error:%d\n", __LINE__, __func__, ret);
+}
+
+
+static void virtio_balloon_page_hinting(VirtIODevice *vdev, VirtQueue *vq)
+{
+ uint64_t addr;
+ uint32_t len;
+ VirtQueueElement elem = {};
+
+ pop_hinting_addr(vq, &addr, &len);
+ page_hinting_request(addr, len);
+ virtqueue_push(vq, &elem, 0);
+ virtio_notify(vdev, vq);
+}
+
static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
{
VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
@@ -443,6 +496,7 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
s->ivq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats);
+ s->hvq = virtio_add_queue(vdev, 128, virtio_balloon_page_hinting);
reset_stats(s);
}
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 311929e..24e26ec 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -825,6 +825,30 @@ static void *virtqueue_alloc_element(size_t sz, unsigned out_num, unsigned in_nu
return elem;
}
+void pop_hinting_addr(VirtQueue *vq, uint64_t *addr, uint32_t *len)
+{
+ VRingMemoryRegionCaches *caches;
+ VRingDesc desc;
+ MemoryRegionCache *desc_cache;
+ VirtIODevice *vdev = vq->vdev;
+ unsigned int head, i, max;
+
+ max = vq->vring.num;
+ if (!virtqueue_get_head(vq, vq->last_avail_idx++, &head)) {
+ printf("\n%d:%sError: Unable to read head\n", __LINE__, __func__);
+ }
+ i = head;
+
+ caches = vring_get_region_caches(vq);
+ if (caches->desc.len < max * sizeof(VRingDesc)) {
+ virtio_error(vdev, "Cannot map descriptor ring");
+ }
+ desc_cache = &caches->desc;
+ vring_desc_read(vdev, &desc, desc_cache, i);
+ *addr = desc.addr;
+ *len = desc.len;
+}
+
void *virtqueue_pop(VirtQueue *vq, size_t sz)
{
unsigned int i, head, max;
diff --git a/include/hw/virtio/virtio-access.h b/include/hw/virtio/virtio-access.h
index 2e92074..568d71f 100644
--- a/include/hw/virtio/virtio-access.h
+++ b/include/hw/virtio/virtio-access.h
@@ -24,6 +24,7 @@
#define LEGACY_VIRTIO_IS_BIENDIAN 1
#endif
+void pop_hinting_addr(VirtQueue *vq, uint64_t *addr, uint32_t *len);
static inline bool virtio_access_is_big_endian(VirtIODevice *vdev)
{
#if defined(LEGACY_VIRTIO_IS_BIENDIAN)
diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h
index 1ea13bd..dfb5782 100644
--- a/include/hw/virtio/virtio-balloon.h
+++ b/include/hw/virtio/virtio-balloon.h
@@ -33,7 +33,7 @@ typedef struct virtio_balloon_stat_modern {
typedef struct VirtIOBalloon {
VirtIODevice parent_obj;
- VirtQueue *ivq, *dvq, *svq;
+ VirtQueue *ivq, *dvq, *svq, *hvq;
uint32_t num_pages;
uint32_t actual;
uint64_t stats[VIRTIO_BALLOON_S_NR];
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 9dd318a..033d64c 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -278,6 +278,11 @@ void qemu_anon_ram_free(void *ptr, size_t size);
#else
#define QEMU_MADV_REMOVE QEMU_MADV_INVALID
#endif
+#ifdef MADV_FREE
+#define QEMU_MADV_FREE MADV_FREE
+#else
+#define QEMU_MADV_FREE QEMU_MAD_INVALID
+#endif
#elif defined(CONFIG_POSIX_MADVISE)
@@ -291,6 +296,7 @@ void qemu_anon_ram_free(void *ptr, size_t size);
#define QEMU_MADV_HUGEPAGE QEMU_MADV_INVALID
#define QEMU_MADV_NOHUGEPAGE QEMU_MADV_INVALID
#define QEMU_MADV_REMOVE QEMU_MADV_INVALID
+#define QEMU_MADV_FREE QEMU_MAD_INVALID
#else /* no-op */
@@ -304,6 +310,7 @@ void qemu_anon_ram_free(void *ptr, size_t size);
#define QEMU_MADV_HUGEPAGE QEMU_MADV_INVALID
#define QEMU_MADV_NOHUGEPAGE QEMU_MADV_INVALID
#define QEMU_MADV_REMOVE QEMU_MADV_INVALID
+#define QEMU_MADV_FREE QEMU_MAD_INVALID
#endif
--
2.9.4
