[PATCH v4] virtio-pci: correctly set virtio pci queue mem multiplier

[Srujana Challa]

Currently, virtio_pci_queue_mem_mult function always returns 4K
when VIRTIO_PCI_FLAG_PAGE_PER_VQ is set. But this won't
work for vhost vdpa when host has page size other than 4K.
This patch introduces a new property(page-per-vdpa-vq) for vdpa
use case to fix the same.

Signed-off-by: Srujana Challa <scha...@marvell.com>
---
v3->v4:
- Return failure if both page_per_vq and host_page_per_vq are set.

v2->v3:
- Modified property name, page-per-vdpa-vq to host-page-per-vq.

v1->v2:
- Introduced a new property to get virtqueue mem multiplier for
  vdpa use case.

 hw/virtio/virtio-pci.c         | 18 ++++++++++++++++--
 include/hw/virtio/virtio-pci.h |  5 +++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 1a7039fb0c..4e31169c6f 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -320,8 +320,12 @@ static bool virtio_pci_ioeventfd_enabled(DeviceState *d)
 
 static inline int virtio_pci_queue_mem_mult(struct VirtIOPCIProxy *proxy)
 {
-    return (proxy->flags & VIRTIO_PCI_FLAG_PAGE_PER_VQ) ?
-        QEMU_VIRTIO_PCI_QUEUE_MEM_MULT : 4;
+    if (proxy->flags & VIRTIO_PCI_FLAG_PAGE_PER_VQ)
+        return QEMU_VIRTIO_PCI_QUEUE_MEM_MULT;
+    else if (proxy->flags & VIRTIO_PCI_FLAG_HOST_PAGE_PER_VQ)
+        return qemu_real_host_page_size();
+    else
+        return 4;
 }
 
 static int virtio_pci_ioeventfd_assign(DeviceState *d, EventNotifier *notifier,
@@ -2108,6 +2112,14 @@ static void virtio_pci_realize(PCIDevice *pci_dev, Error 
**errp)
         proxy->flags &= ~VIRTIO_PCI_FLAG_USE_IOEVENTFD;
     }
 
+    if ((proxy->flags & VIRTIO_PCI_FLAG_PAGE_PER_VQ) &&
+        (proxy->flags & VIRTIO_PCI_FLAG_HOST_PAGE_PER_VQ)) {
+        error_setg(errp, "device cannot work with both page-per-vq and"
+                   " host-page-per-vq at the same time");
+        error_append_hint(errp, "Set either page-per-vq or 
host-page-per-vq\n");
+        return;
+    }
+
     /*
      * virtio pci bar layout used by default.
      * subclasses can re-arrange things if needed.
@@ -2301,6 +2313,8 @@ static Property virtio_pci_properties[] = {
                     VIRTIO_PCI_FLAG_INIT_FLR_BIT, true),
     DEFINE_PROP_BIT("aer", VirtIOPCIProxy, flags,
                     VIRTIO_PCI_FLAG_AER_BIT, false),
+    DEFINE_PROP_BIT("host-page-per-vq", VirtIOPCIProxy, flags,
+                    VIRTIO_PCI_FLAG_HOST_PAGE_PER_VQ_BIT, false),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/include/hw/virtio/virtio-pci.h b/include/hw/virtio/virtio-pci.h
index 59d88018c1..81b6de4291 100644
--- a/include/hw/virtio/virtio-pci.h
+++ b/include/hw/virtio/virtio-pci.h
@@ -43,6 +43,7 @@ enum {
     VIRTIO_PCI_FLAG_INIT_FLR_BIT,
     VIRTIO_PCI_FLAG_AER_BIT,
     VIRTIO_PCI_FLAG_ATS_PAGE_ALIGNED_BIT,
+    VIRTIO_PCI_FLAG_HOST_PAGE_PER_VQ_BIT,
 };
 
 /* Need to activate work-arounds for buggy guests at vmstate load. */
@@ -89,6 +90,10 @@ enum {
 #define VIRTIO_PCI_FLAG_ATS_PAGE_ALIGNED \
   (1 << VIRTIO_PCI_FLAG_ATS_PAGE_ALIGNED_BIT)
 
+/* page per vdpa vq flag to be used for vhost vdpa backends */
+#define VIRTIO_PCI_FLAG_HOST_PAGE_PER_VQ \
+    (1 << VIRTIO_PCI_FLAG_HOST_PAGE_PER_VQ_BIT)
+
 typedef struct {
     MSIMessage msg;
     int virq;
-- 
2.25.1