Re: [PATCH 1/3] Enable non page boundary BAR device assignment

Alexander Graf
2009-12-15T18:47:37Z

Michael S. Tsirkin wrote:
> On Tue, Dec 15, 2009 at 07:30:26PM +0100, Alexander Graf wrote:
>
>> While trying to get device passthrough working with an emulex hba, kvm
>> refused to pass it through because it has a BAR of 256 bytes:
>>
>> Region 0: Memory at d2100000 (64-bit, non-prefetchable) [size=4K]
>> Region 2: Memory at d2101000 (64-bit, non-prefetchable) [size=256]
>> Region 4: I/O ports at b100 [size=256]
>>
>> Since the page boundary is an arbitrary optimization to allow 1:1 mapping of
>> physical to virtual addresses, we can still take the old MMIO callback route.
>>
>> So let's add a second code path that allows for size & 0xFFF != 0 sized regions
>> by looping it through userspace.
>>
>> I verified that it works by passing through an e1000 with this additional patch
>> applied and the card acted the same way it did without this patch:
>>
>> map_func = assigned_dev_iomem_map;
>> - if (cur_region->size & 0xFFF) {
>> + if (i != PCI_ROM_SLOT){
>> fprintf(stderr, "PCI region %d at address 0x%llx "
>>
>> Signed-off-by: Alexander Graf <agraf@suse.de>
>>
>
>
> Looks good.
> 1 question:
>
>
>> ---
>>
>> v1 -> v2:
>>
>> - don't use map_func function pointer
>> - use the same code for mmap on fast and slow path
>>
>> v2 -> v3:
>>
>> - address mst's comments
>> ---
>> hw/device-assignment.c | 117 +++++++++++++++++++++++++++++++++++++++++++++--
>> 1 files changed, 112 insertions(+), 5 deletions(-)
>>
>> diff --git a/hw/device-assignment.c b/hw/device-assignment.c
>> index 13a86bb..000fa61 100644
>> --- a/hw/device-assignment.c
>> +++ b/hw/device-assignment.c
>> @@ -148,6 +148,105 @@ static uint32_t assigned_dev_ioport_readl(void *opaque, uint32_t addr)
>> return value;
>> }
>>
>> +static uint32_t slow_bar_readb(void *opaque, target_phys_addr_t addr)
>> +{
>> + AssignedDevRegion *d = opaque;
>> + uint8_t *in = d->u.r_virtbase + addr;
>> + uint32_t r;
>> +
>> + r = *in;
>> + DEBUG("slow_bar_readl addr=0x" TARGET_FMT_plx " val=0x%08x\n", addr, r);
>> +
>> + return r;
>> +}
>> +
>> +static uint32_t slow_bar_readw(void *opaque, target_phys_addr_t addr)
>> +{
>> + AssignedDevRegion *d = opaque;
>> + uint16_t *in = d->u.r_virtbase + addr;
>> + uint32_t r;
>> +
>> + r = *in;
>> + DEBUG("slow_bar_readl addr=0x" TARGET_FMT_plx " val=0x%08x\n", addr, r);
>> +
>> + return r;
>> +}
>> +
>> +static uint32_t slow_bar_readl(void *opaque, target_phys_addr_t addr)
>> +{
>> + AssignedDevRegion *d = opaque;
>> + uint32_t *in = d->u.r_virtbase + addr;
>> + uint32_t r;
>> +
>> + r = *in;
>> + DEBUG("slow_bar_readl addr=0x" TARGET_FMT_plx " val=0x%08x\n", addr, r);
>> +
>> + return r;
>> +}
>> +
>> +static void slow_bar_writeb(void *opaque, target_phys_addr_t addr, uint32_t val)
>> +{
>> + AssignedDevRegion *d = opaque;
>> + uint8_t *out = d->u.r_virtbase + addr;
>> +
>> + DEBUG("slow_bar_writeb addr=0x" TARGET_FMT_plx " val=0x%02x\n", addr, val);
>> + *out = val;
>> +}
>> +
>> +static void slow_bar_writew(void *opaque, target_phys_addr_t addr, uint32_t val)
>> +{
>> + AssignedDevRegion *d = opaque;
>> + uint16_t *out = d->u.r_virtbase + addr;
>> +
>> + DEBUG("slow_bar_writew addr=0x" TARGET_FMT_plx " val=0x%04x\n", addr, val);
>> + *out = val;
>> +}
>> +
>> +static void slow_bar_writel(void *opaque, target_phys_addr_t addr, uint32_t val)
>> +{
>> + AssignedDevRegion *d = opaque;
>> + uint32_t *out = d->u.r_virtbase + addr;
>> +
>> + DEBUG("slow_bar_writel addr=0x" TARGET_FMT_plx " val=0x%08x\n", addr, val);
>> + *out = val;
>> +}
>> +
>> +static CPUWriteMemoryFunc * const slow_bar_write[] = {
>> + &slow_bar_writeb,
>> + &slow_bar_writew,
>> + &slow_bar_writel
>> +};
>> +
>> +static CPUReadMemoryFunc * const slow_bar_read[] = {
>> + &slow_bar_readb,
>> + &slow_bar_readw,
>> + &slow_bar_readl
>> +};
>> +
>> +static void assigned_dev_iomem_map_slow(PCIDevice *pci_dev, int region_num,
>> + pcibus_t e_phys, pcibus_t e_size,
>> + int type)
>> +{
>> + AssignedDevice *r_dev = container_of(pci_dev, AssignedDevice, dev);
>> + AssignedDevRegion *region = &r_dev->v_addrs[region_num];
>> + PCIRegion *real_region = &r_dev->real_device.regions[region_num];
>> + int m;
>> +
>> + DEBUG("slow map\n");
>> + m = cpu_register_io_memory(slow_bar_read, slow_bar_write, region);
>> + cpu_register_physical_memory(e_phys, e_size, m);
>> +
>> + /* MSI-X MMIO page */
>> + if ((e_size > 0) &&
>> + real_region->base_addr <= r_dev->msix_table_addr &&
>> + real_region->base_addr + real_region->size >= r_dev->msix_table_addr) {
>> + int offset = r_dev->msix_table_addr - real_region->base_addr;
>> +
>> + cpu_register_physical_memory(e_phys + offset,
>> + TARGET_PAGE_SIZE, r_dev->mmio_index);
>> + }
>> +}
>> +
>> static void assigned_dev_iomem_map(PCIDevice *pci_dev, int region_num,
>> pcibus_t e_phys, pcibus_t e_size, int type)
>> {
>> @@ -381,15 +480,22 @@ static int assigned_dev_register_regions(PCIRegion *io_regions,
>>
>> /* handle memory io regions */
>> if (cur_region->type & IORESOURCE_MEM) {
>> + int slow_map = 0;
>> int t = cur_region->type & IORESOURCE_PREFETCH
>> ? PCI_BASE_ADDRESS_MEM_PREFETCH
>> : PCI_BASE_ADDRESS_SPACE_MEMORY;
>> +
>> if (cur_region->size & 0xFFF) {
>> - fprintf(stderr, "Unable to assign device: PCI region %d "
>> - "at address 0x%llx has size 0x%x, "
>> - " which is not a multiple of 4K\n",
>> + fprintf(stderr, "PCI region %d at address 0x%llx "
>> + "has size 0x%x, which is not a multiple of 4K. "
>> + "You might experience some performance hit due to that.\n",
>> i, (unsigned long long)cur_region->base_addr,
>> cur_region->size);
>> + slow_map = 1;
>> + }
>> +
>> + if (slow_map && (i == PCI_ROM_SLOT)) {
>> + fprintf(stderr, "ROM not aligned - can't continue\n");
>> return -1;
>>
>
> Why is this? Can't ROM be handled in the same way?
> I think it was previously ...
>

You can't execute code from MMIO regions, so slow_map doesn't work there.

>
>> }
>>
>> @@ -405,7 +511,7 @@ static int assigned_dev_register_regions(PCIRegion *io_regions,
>> } else {
>> pci_dev->v_addrs[i].u.r_virtbase =
>> mmap(NULL,
>> - (cur_region->size + 0xFFF) & 0xFFFFF000,
>> + cur_region->size,
>>
>
> Hmm, one assumes this code did work at some point ...
> do you know why was it done this way?
>

Nope :-).

Alex