virtio-pci: compat page aligned ATS

Commit 4c70875372b8 ("pci: advertise a page aligned ATS") advertises
the page aligned via ATS capability (RO) to unbrek recent Linux IOMMU
drivers since 5.2. But it forgot the compat the capability which
breaks the migration from old machine type:

(qemu) qemu-kvm: get_pci_config_device: Bad config data: i=0x104 read:
0 device: 20 cmask: ff wmask: 0 w1cmask:0

This patch introduces a new parameter "x-ats-page-aligned" for
virtio-pci device and turns it on for machine type which is newer than
5.1.

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: qemu-stable@nongnu.org
Fixes: 4c70875372b8 ("pci: advertise a page aligned ATS")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20210406040330.11306-1-jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

4 files changed, 16 insertions, 5 deletions

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 9935c6ddd5..a50f2d5f0a 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -53,6 +53,7 @@ GlobalProperty hw_compat_5_1[] = {
     { "nvme", "use-intel-id", "on"},
     { "pvpanic", "events", "1"}, /* PVPANIC_PANICKED */
     { "pl011", "migrate-clk", "off" },
+    { "virtio-pci", "x-ats-page-aligned", "off"},
 };
 const size_t hw_compat_5_1_len = G_N_ELEMENTS(hw_compat_5_1);
 
diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
index a733e2fb87..fd0fa157e8 100644
--- a/hw/pci/pcie.c
+++ b/hw/pci/pcie.c
@@ -963,16 +963,18 @@ void pcie_dev_ser_num_init(PCIDevice *dev, uint16_t offset, uint64_t ser_num)
     pci_set_quad(dev->config + offset + pci_dsn_cap, ser_num);
 }
 
-void pcie_ats_init(PCIDevice *dev, uint16_t offset)
+void pcie_ats_init(PCIDevice *dev, uint16_t offset, bool aligned)
 {
     pcie_add_capability(dev, PCI_EXT_CAP_ID_ATS, 0x1,
                         offset, PCI_EXT_CAP_ATS_SIZEOF);
 
     dev->exp.ats_cap = offset;
 
-    /* Invalidate Queue Depth 0, Page Aligned Request 1 */
-    pci_set_word(dev->config + offset + PCI_ATS_CAP,
-                 PCI_ATS_CAP_PAGE_ALIGNED);
+    /* Invalidate Queue Depth 0 */
+    if (aligned) {
+        pci_set_word(dev->config + offset + PCI_ATS_CAP,
+                     PCI_ATS_CAP_PAGE_ALIGNED);
+    }
     /* STU 0, Disabled by default */
     pci_set_word(dev->config + offset + PCI_ATS_CTRL, 0);
 
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index c1b67cf6fc..b321604d9b 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1856,7 +1856,8 @@ static void virtio_pci_realize(PCIDevice *pci_dev, Error **errp)
         }
 
         if (proxy->flags & VIRTIO_PCI_FLAG_ATS) {
-            pcie_ats_init(pci_dev, last_pcie_cap_offset);
+            pcie_ats_init(pci_dev, last_pcie_cap_offset,
+                          proxy->flags & VIRTIO_PCI_FLAG_ATS_PAGE_ALIGNED);
             last_pcie_cap_offset += PCI_EXT_CAP_ATS_SIZEOF;
         }
 
@@ -1933,6 +1934,8 @@ static Property virtio_pci_properties[] = {
                      ignore_backend_features, false),
     DEFINE_PROP_BIT("ats", VirtIOPCIProxy, flags,
                     VIRTIO_PCI_FLAG_ATS_BIT, false),
+    DEFINE_PROP_BIT("x-ats-page-aligned", VirtIOPCIProxy, flags,
+                    VIRTIO_PCI_FLAG_ATS_PAGE_ALIGNED_BIT, true),
     DEFINE_PROP_BIT("x-pcie-deverr-init", VirtIOPCIProxy, flags,
                     VIRTIO_PCI_FLAG_INIT_DEVERR_BIT, true),
     DEFINE_PROP_BIT("x-pcie-lnkctl-init", VirtIOPCIProxy, flags,
diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h
index d7d5d403a9..2446dcd9ae 100644
--- a/hw/virtio/virtio-pci.h
+++ b/hw/virtio/virtio-pci.h
@@ -42,6 +42,7 @@ enum {
     VIRTIO_PCI_FLAG_INIT_PM_BIT,
     VIRTIO_PCI_FLAG_INIT_FLR_BIT,
     VIRTIO_PCI_FLAG_AER_BIT,
+    VIRTIO_PCI_FLAG_ATS_PAGE_ALIGNED_BIT,
 };
 
 /* Need to activate work-arounds for buggy guests at vmstate load. */
@@ -84,6 +85,10 @@ enum {
 /* Advanced Error Reporting capability */
 #define VIRTIO_PCI_FLAG_AER (1 << VIRTIO_PCI_FLAG_AER_BIT)
 
+/* Page Aligned Address space Translation Service */
+#define VIRTIO_PCI_FLAG_ATS_PAGE_ALIGNED \
+  (1 << VIRTIO_PCI_FLAG_ATS_PAGE_ALIGNED_BIT)
+
 typedef struct {
     MSIMessage msg;
     int virq;