[PATCH 16/16] kvm: emulate command register for SRIOV virtual function

[Sheng Yang <sheng@xxxxxxxxxxxxxxx>]

MMIO enable byte would be checked when enabling virtual function, but in fact,
the whole virtual function's command register is hard-wired to zero... So when
guest read from command register it would only get 0, specially for MMIO enable
bit. And this result in, if guest driver want to do a RMW to the command
register, it would always get 0 and override former setting (e.g. unmap MMIO by
set the correlated bit to zero)...

Then we relay on QEmu to provide a reasonable command register content to guest.

Signed-off-by: Sheng Yang <sheng@xxxxxxxxxxxxxxx>
---
 qemu/hw/device-assignment.c |   13 ++++++++++++-
 qemu/hw/device-assignment.h |    1 +
 2 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/qemu/hw/device-assignment.c b/qemu/hw/device-assignment.c
index fb48cdc..a5ccdd9 100644
--- a/qemu/hw/device-assignment.c
+++ b/qemu/hw/device-assignment.c
@@ -26,7 +26,10 @@
  *  Copyright (C) 2008, IBM, Muli Ben-Yehuda (muli@xxxxxxxxxx)
  */
 #include <stdio.h>
+#include <unistd.h>
 #include <sys/io.h>
+#include <sys/types.h>
+#include <sys/stat.h>
 #include "qemu-kvm.h"
 #include "hw.h"
 #include "pc.h"
@@ -317,7 +320,7 @@ static uint32_t assigned_dev_pci_read_config(PCIDevice *d, uint32_t address,
     ssize_t ret;
     AssignedDevice *pci_dev = container_of(d, AssignedDevice, dev);
 
-    if (address < 0x4 ||
+    if (address < 0x4 || (pci_dev->need_emulate_cmd && address == 0x4) ||
 	(address >= 0x10 && address <= 0x24) || address == 0x34 ||
         address == 0x3c || address == 0x3d ||
         pci_access_cap_config(d, address, len)) {
@@ -431,6 +434,7 @@ static int get_real_device(AssignedDevice *pci_dev, uint8_t r_bus,
     FILE *f;
     unsigned long long start, end, size, flags;
     unsigned long id;
+    struct stat statbuf;
     PCIRegion *rp;
     PCIDevRegions *dev = &pci_dev->real_device;
 
@@ -519,6 +523,13 @@ again:
     }
     fclose(f);
 
+    /* dealing with virtual function device */
+    snprintf(name, sizeof(name), "%sphysfn/", dir);
+    if (!stat(name, &statbuf))
+	    pci_dev->need_emulate_cmd = 1;
+    else
+	    pci_dev->need_emulate_cmd = 0;
+
     dev->region_number = r;
     return 0;
 }
diff --git a/qemu/hw/device-assignment.h b/qemu/hw/device-assignment.h
index 85ed949..32d958c 100644
--- a/qemu/hw/device-assignment.h
+++ b/qemu/hw/device-assignment.h
@@ -97,6 +97,7 @@ typedef struct {
     void *msix_table_page;
     target_phys_addr_t msix_table_addr;
     int mmio_index;
+    int need_emulate_cmd;
 } AssignedDevice;
 
 typedef struct AssignedDevInfo AssignedDevInfo;
-- 
1.5.4.5

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