[patch 0/3] QEMU: virtio should register power of two sized regions

[patch 0/3] QEMU: virtio should register power of two sized regions

[Marcelo Tosatti]

Otherwise the guest will miscalculate the region size.

-- 


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[patch 1/3] QEMU/KVM: add fls()

[Marcelo Tosatti]

[-- Attachment #1: add-fls --]
[-- Type: text/plain, Size: 1170 bytes --]

Find Last Set, in accordance with glibc's ffs.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: kvm-userspace.hotplug3/qemu/cutils.c
===================================================================
--- kvm-userspace.hotplug3.orig/qemu/cutils.c
+++ kvm-userspace.hotplug3/qemu/cutils.c
@@ -135,3 +135,14 @@ char *urldecode(const char *ptr)
     return ret;
 }
 
+int fls(int i)
+{
+    int bit;
+
+    for (bit=31; bit >= 0; bit--)
+        if (i & (1 << bit))
+            return bit+1;
+
+    return 0;
+}
+
Index: kvm-userspace.hotplug3/qemu/qemu-common.h
===================================================================
--- kvm-userspace.hotplug3.orig/qemu/qemu-common.h
+++ kvm-userspace.hotplug3/qemu/qemu-common.h
@@ -87,6 +87,7 @@ int stristart(const char *str, const cha
 time_t mktimegm(struct tm *tm);
 int hex2bin(char ch);
 char *urldecode(const char *ptr);
+int fls(int i);
 
 /* Error handling.  */
 

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[patch 2/3] QEMU/KVM: virtio register pow2 memory regions

[Marcelo Tosatti]

[-- Attachment #1: fix-virtio --]
[-- Type: text/plain, Size: 1256 bytes --]

Otherwise the PCI size for such regions will be calculated erroneously.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Anthony Liguori <anthony@codemonkey.ws>

Index: kvm-userspace.hotplug3/qemu/hw/virtio.c
===================================================================
--- kvm-userspace.hotplug3.orig/qemu/hw/virtio.c
+++ kvm-userspace.hotplug3/qemu/hw/virtio.c
@@ -404,6 +404,7 @@ VirtIODevice *virtio_init_pci(PCIBus *bu
     VirtIODevice *vdev;
     PCIDevice *pci_dev;
     uint8_t *config;
+    uint32_t size;
 
     pci_dev = pci_register_device(bus, name, struct_size,
 				  -1, NULL, NULL);
@@ -441,7 +442,11 @@ VirtIODevice *virtio_init_pci(PCIBus *bu
     else
 	vdev->config = NULL;
 
-    pci_register_io_region(pci_dev, 0, 20 + config_size, PCI_ADDRESS_SPACE_IO,
+    size = 20 + config_size;
+    if (size & (size-1))
+        size = 1 << fls(size);
+
+    pci_register_io_region(pci_dev, 0, size, PCI_ADDRESS_SPACE_IO,
 			   virtio_map);
     qemu_register_reset(virtio_reset, vdev);
 

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[patch 3/3] QEMU/KVM: bail out if PCI region is not power of two

[Marcelo Tosatti]

[-- Attachment #1: pci-warn-region-mem --]
[-- Type: text/plain, Size: 859 bytes --]

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: kvm-userspace.hotplug3/qemu/hw/pci.c
===================================================================
--- kvm-userspace.hotplug3.orig/qemu/hw/pci.c
+++ kvm-userspace.hotplug3/qemu/hw/pci.c
@@ -236,6 +236,11 @@ void pci_register_io_region(PCIDevice *p
 
     if ((unsigned int)region_num >= PCI_NUM_REGIONS)
         return;
+
+    if (size & (size-1))
+        term_printf("WARNING: PCI region size must be pow2 "
+                    "type=0x%x, size=0x%x\n", type, size);
+
     r = &pci_dev->io_regions[region_num];
     r->addr = -1;
     r->size = size;

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Re: [patch 0/3] QEMU: virtio should register power of two sized regions

[Avi Kivity]

Marcelo Tosatti wrote:
> Otherwise the guest will miscalculate the region size.
>
>   
Applied all, thanks.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.


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