[Qemu-devel] [PATCH v2 0/2] vfio: Another try to fix ROM BAR endianness

[Qemu-devel] [PATCH v2 0/2] vfio: Another try to fix ROM BAR endianness

[Alexey Kardashevskiy]

I did some tests on LE/BE guest/host combinations and came up with
these 2 patches. Please comment. Thanks.

Changes:
v2:
* tested TCG
* updated commit logs



Alexey Kardashevskiy (1):
  Revert "vfio: Make BARs native endian"

Nikunj A Dadhania (1):
  vfio: make rom read endian sensitive

 hw/misc/vfio.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

-- 
2.0.0

[Qemu-devel] [PATCH v2 1/2] Revert "vfio: Make BARs native endian"

[Alexey Kardashevskiy]

This reverts commit c40708176a6b52b73bec14796b7c71b882ceb102.

The resulting code wrongly assumed target and host endianness are
the same which is not always the case for PPC64.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
Changes:
v2:
* simplified commit log (thanks to Greg Kurz)
---
 hw/misc/vfio.c | 41 ++++++++++-------------------------------
 1 file changed, 10 insertions(+), 31 deletions(-)

diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
index 40dcaa6..22ebcbd 100644
--- a/hw/misc/vfio.c
+++ b/hw/misc/vfio.c
@@ -1098,10 +1098,10 @@ static void vfio_bar_write(void *opaque, hwaddr addr,
         buf.byte = data;
         break;
     case 2:
-        buf.word = data;
+        buf.word = cpu_to_le16(data);
         break;
     case 4:
-        buf.dword = data;
+        buf.dword = cpu_to_le32(data);
         break;
     default:
         hw_error("vfio: unsupported write size, %d bytes", size);
@@ -1158,10 +1158,10 @@ static uint64_t vfio_bar_read(void *opaque,
         data = buf.byte;
         break;
     case 2:
-        data = buf.word;
+        data = le16_to_cpu(buf.word);
         break;
     case 4:
-        data = buf.dword;
+        data = le32_to_cpu(buf.dword);
         break;
     default:
         hw_error("vfio: unsupported read size, %d bytes", size);
@@ -1188,7 +1188,7 @@ static uint64_t vfio_bar_read(void *opaque,
 static const MemoryRegionOps vfio_bar_ops = {
     .read = vfio_bar_read,
     .write = vfio_bar_write,
-    .endianness = DEVICE_NATIVE_ENDIAN,
+    .endianness = DEVICE_LITTLE_ENDIAN,
 };
 
 static void vfio_pci_load_rom(VFIODevice *vdev)
@@ -1250,42 +1250,21 @@ static void vfio_pci_load_rom(VFIODevice *vdev)
 static uint64_t vfio_rom_read(void *opaque, hwaddr addr, unsigned size)
 {
     VFIODevice *vdev = opaque;
-    union {
-        uint8_t byte;
-        uint16_t word;
-        uint32_t dword;
-        uint64_t qword;
-    } buf;
-    uint64_t data = 0;
+    uint64_t val = ((uint64_t)1 << (size * 8)) - 1;
 
     /* Load the ROM lazily when the guest tries to read it */
     if (unlikely(!vdev->rom && !vdev->rom_read_failed)) {
         vfio_pci_load_rom(vdev);
     }
 
-    memcpy(&buf, vdev->rom + addr,
+    memcpy(&val, vdev->rom + addr,
            (addr < vdev->rom_size) ? MIN(size, vdev->rom_size - addr) : 0);
 
-    switch (size) {
-    case 1:
-        data = buf.byte;
-        break;
-    case 2:
-        data = buf.word;
-        break;
-    case 4:
-        data = buf.dword;
-        break;
-    default:
-        hw_error("vfio: unsupported read size, %d bytes", size);
-        break;
-    }
-
     DPRINTF("%s(%04x:%02x:%02x.%x, 0x%"HWADDR_PRIx", 0x%x) = 0x%"PRIx64"\n",
             __func__, vdev->host.domain, vdev->host.bus, vdev->host.slot,
-            vdev->host.function, addr, size, data);
+            vdev->host.function, addr, size, val);
 
-    return data;
+    return val;
 }
 
 static void vfio_rom_write(void *opaque, hwaddr addr,
@@ -1296,7 +1275,7 @@ static void vfio_rom_write(void *opaque, hwaddr addr,
 static const MemoryRegionOps vfio_rom_ops = {
     .read = vfio_rom_read,
     .write = vfio_rom_write,
-    .endianness = DEVICE_NATIVE_ENDIAN,
+    .endianness = DEVICE_LITTLE_ENDIAN,
 };
 
 static bool vfio_blacklist_opt_rom(VFIODevice *vdev)
-- 
2.0.0

[Qemu-devel] [PATCH v2 2/2] vfio: make rom read endian sensitive

[Alexey Kardashevskiy]

From: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>

All memory regions used by VFIO are LITTLE_ENDIAN and they
already take care of endiannes when accessing real device BARs
except ROM - it was broken on BE hosts.

This fixes endiannes for ROM BARs the same way as it is done
for other BARs.

This has been tested on PPC64 BE/LE host/guest in all possible
combinations including TCG.

Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
[aik: added commit log]
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
Changes:
v2:
* add statement where it was tested
---
 hw/misc/vfio.c | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
index 22ebcbd..d66f3d2 100644
--- a/hw/misc/vfio.c
+++ b/hw/misc/vfio.c
@@ -1250,7 +1250,13 @@ static void vfio_pci_load_rom(VFIODevice *vdev)
 static uint64_t vfio_rom_read(void *opaque, hwaddr addr, unsigned size)
 {
     VFIODevice *vdev = opaque;
-    uint64_t val = ((uint64_t)1 << (size * 8)) - 1;
+    union {
+        uint8_t byte;
+        uint16_t word;
+        uint32_t dword;
+        uint64_t qword;
+    } val;
+    uint64_t data = 0;
 
     /* Load the ROM lazily when the guest tries to read it */
     if (unlikely(!vdev->rom && !vdev->rom_read_failed)) {
@@ -1260,11 +1266,26 @@ static uint64_t vfio_rom_read(void *opaque, hwaddr addr, unsigned size)
     memcpy(&val, vdev->rom + addr,
            (addr < vdev->rom_size) ? MIN(size, vdev->rom_size - addr) : 0);
 
+    switch (size) {
+    case 1:
+        data = val.byte;
+        break;
+    case 2:
+        data = le16_to_cpu(val.word);
+        break;
+    case 4:
+        data = le32_to_cpu(val.dword);
+        break;
+    default:
+        hw_error("vfio: unsupported read size, %d bytes\n", size);
+        break;
+    }
+
     DPRINTF("%s(%04x:%02x:%02x.%x, 0x%"HWADDR_PRIx", 0x%x) = 0x%"PRIx64"\n",
             __func__, vdev->host.domain, vdev->host.bus, vdev->host.slot,
-            vdev->host.function, addr, size, val);
+            vdev->host.function, addr, size, data);
 
-    return val;
+    return data;
 }
 
 static void vfio_rom_write(void *opaque, hwaddr addr,
-- 
2.0.0