[Qemu-devel] [PATCH v2] virtio-pci: Add Function Level Reset support

[Julia Suvorova <jusual@redhat.com>]

Using FLR becomes convenient in cases where resetting the bus is
impractical, for example, when debugging the behavior of individual
functions.

Signed-off-by: Julia Suvorova <jusual@redhat.com>
---
Requires definition of 4.2 machines:
Based-on: <20190724103524.20916-1-cohuck@redhat.com>

v2:
    Add compatibility property "x-pcie-flr-init"

 hw/core/machine.c      |  4 +++-
 hw/virtio/virtio-pci.c | 10 ++++++++++
 hw/virtio/virtio-pci.h |  4 ++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 83cd1bfeec..829ada099e 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -27,7 +27,9 @@
 #include "hw/pci/pci.h"
 #include "hw/mem/nvdimm.h"
 
-GlobalProperty hw_compat_4_1[] = {};
+GlobalProperty hw_compat_4_1[] = {
+    { "virtio-pci", "x-pcie-flr-init", "off" },
+};
 const size_t hw_compat_4_1_len = G_N_ELEMENTS(hw_compat_4_1);
 
 GlobalProperty hw_compat_4_0[] = {
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 8babd92e59..0075b3e2af 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -601,6 +601,10 @@ static void virtio_write_config(PCIDevice *pci_dev, uint32_t address,
 
     pci_default_write_config(pci_dev, address, val, len);
 
+    if (proxy->flags & VIRTIO_PCI_FLAG_INIT_FLR) {
+        pcie_cap_flr_write_config(pci_dev, address, val, len);
+    }
+
     if (range_covers_byte(address, len, PCI_COMMAND) &&
         !(pci_dev->config[PCI_COMMAND] & PCI_COMMAND_MASTER)) {
         virtio_pci_stop_ioeventfd(proxy);
@@ -1777,6 +1781,10 @@ static void virtio_pci_realize(PCIDevice *pci_dev, Error **errp)
             pcie_ats_init(pci_dev, 256);
         }
 
+        if (proxy->flags & VIRTIO_PCI_FLAG_INIT_FLR) {
+            /* Set Function Level Reset capability bit */
+            pcie_cap_flr_init(pci_dev);
+        }
     } else {
         /*
          * make future invocations of pci_is_express() return false
@@ -1844,6 +1852,8 @@ static Property virtio_pci_properties[] = {
                     VIRTIO_PCI_FLAG_INIT_LNKCTL_BIT, true),
     DEFINE_PROP_BIT("x-pcie-pm-init", VirtIOPCIProxy, flags,
                     VIRTIO_PCI_FLAG_INIT_PM_BIT, true),
+    DEFINE_PROP_BIT("x-pcie-flr-init", VirtIOPCIProxy, flags,
+                    VIRTIO_PCI_FLAG_INIT_FLR_BIT, true),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h
index 292275acb1..e2eaaa9182 100644
--- a/hw/virtio/virtio-pci.h
+++ b/hw/virtio/virtio-pci.h
@@ -44,6 +44,7 @@ enum {
     VIRTIO_PCI_FLAG_INIT_DEVERR_BIT,
     VIRTIO_PCI_FLAG_INIT_LNKCTL_BIT,
     VIRTIO_PCI_FLAG_INIT_PM_BIT,
+    VIRTIO_PCI_FLAG_INIT_FLR_BIT,
 };
 
 /* Need to activate work-arounds for buggy guests at vmstate load. */
@@ -80,6 +81,9 @@ enum {
 /* Init Power Management */
 #define VIRTIO_PCI_FLAG_INIT_PM (1 << VIRTIO_PCI_FLAG_INIT_PM_BIT)
 
+/* Init Function Level Reset capability */
+#define VIRTIO_PCI_FLAG_INIT_FLR (1 << VIRTIO_PCI_FLAG_INIT_FLR_BIT)
+
 typedef struct {
     MSIMessage msg;
     int virq;
-- 
2.21.0