On Thu, 2013-03-28 at 11:03 +0100, Paolo Bonzini wrote:
> Il 28/03/2013 10:04, Michael S. Tsirkin ha scritto:
> >>> > > Got ranges_overlap for vq: 0 ring_phys: 0 ring_size: 1028
> >>> > > Checking vq: 1 ring_phys: 0 ring_size: 1028 >>>>>>>>>>>>>>>>>>.
> >>> > > Got ranges_overlap for vq: 1 ring_phys: 0 ring_size: 1028
> >>> > > Checking vq: 2 ring_phys: ed000 ring_size: 5124 >>>>>>>>>>>>>>>>>>.
> >>> > > Calling l: 5124 for start_addr: c0000 for vq 2
> >>> > > Unable to map ring buffer for ring 2
> >>> > > l: 4096 ring_size: 5124
> > okay so the ring address is within ROM.
> > Unsurprisingly it fails.
> > bios should stop device before write protect.
> >
>
> The above log is very early, when everything is RAM:
>
> vhost_set_memory: section: 0x7fe2801f2b60 section->size: 2146697216 add: 0
> Before vhost_verify_ring_mappings: start_addr: c0000 size: 2146697216
>
> The rings are not within ROM. ROM is at 0xc0000-0xcc000 according to the
> PAM registers.
>
> The way I followed the debug output, "Got ranges_overlap" means
> actually "bailing out because ranges do not overlap".
Yes, this is when !ranges_overlap() is hit in
vhost_verify_ring_mappings(), so the offending cpu_physical_memory_map()
is skipped..
> In particular,
> here all three virtqueues fail the test, because this is the ROM area
> 0xc0000..0xc7fff:
>
> vhost_set_memory: section: 0x7fe2801f2aa0 section->size: 32768 add: 1
> Before vhost_verify_ring_mappings: start_addr: c0000 size: 32768
> Checking vq: 0 ring_phys: 0 ring_size: 1028 >>>>>>>>>>>>>>>>>>.
> Got ranges_overlap for vq: 0 ring_phys: 0 ring_size: 1028
> Checking vq: 1 ring_phys: 0 ring_size: 1028 >>>>>>>>>>>>>>>>>>.
> Got ranges_overlap for vq: 1 ring_phys: 0 ring_size: 1028
> Checking vq: 2 ring_phys: ed000 ring_size: 5124 >>>>>>>>>>>>>>>>>>.
> Got ranges_overlap for vq: 2 ring_phys: ed000 ring_size: 5124
>
> Just below, vhost looks at the large RAM area starting at 0xc8000
> (it's large because 0xf0000..0xfffff is still RAM):
>
> vhost_set_memory: section: 0x7fe2801f2aa0 section->size: 2146664448 add: 1
> Before vhost_verify_ring_mappings: start_addr: c8000 size: 2146664448
> Checking vq: 0 ring_phys: 0 ring_size: 1028 >>>>>>>>>>>>>>>>>>.
> Got ranges_overlap for vq: 0 ring_phys: 0 ring_size: 1028
> Checking vq: 1 ring_phys: 0 ring_size: 1028 >>>>>>>>>>>>>>>>>>.
> Got ranges_overlap for vq: 1 ring_phys: 0 ring_size: 1028
> Checking vq: 2 ring_phys: ed000 ring_size: 5124 >>>>>>>>>>>>>>>>>>.
> Calling l: 5124 for start_addr: c8000 for vq 2
>
> Here vq 0 and 1 fail the test because they are in low RAM, vq 2 passes.
>
> After 0xf0000..0xfffff is marked readonly,
Btw, the first vhost_set_memory() and failing
vhost_verify_ring_mappings() do not occur until the
pci_config_writeb(..., 0x31) code is executed in
src/shadow.c:make_bios_readonly_intel() below:
static void
make_bios_readonly_intel(u16 bdf, u32 pam0)
{
// Flush any pending writes before locking memory.
wbinvd();
// Write protect roms from 0xc0000-0xf0000
u32 romend = rom_get_last(), romtop = rom_get_max();
int i;
for (i=0; i<6; i++) {
u32 mem = BUILD_ROM_START + i * 32*1024;
u32 pam = pam0 + 1 + i;
if (romend <= mem + 16*1024 || romtop <= mem + 32*1024) {
if (romend > mem && romtop > mem + 16*1024)
pci_config_writeb(bdf, pam, 0x31);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
break;
}
pci_config_writeb(bdf, pam, 0x11);
}
// Write protect 0xf0000-0x100000
pci_config_writeb(bdf, pam0, 0x10);
}
Up until this point, vhost_verify_ring_mappings() is not called by
vhost_set_memory() as vhost_dev_start() has not been invoked to set
vdev->started yet..
> vhost looks at the RAM
> between 0xc9000 and 0xf0000:
>
> vhost_set_memory: section: 0x7fe2801f2aa0 section->size: 159744 add: 1
> Before vhost_verify_ring_mappings: start_addr: c9000 size: 159744
> Checking vq: 0 ring_phys: 0 ring_size: 1028 >>>>>>>>>>>>>>>>>>.
> Got ranges_overlap for vq: 0 ring_phys: 0 ring_size: 1028
> Checking vq: 1 ring_phys: 0 ring_size: 1028 >>>>>>>>>>>>>>>>>>.
> Got ranges_overlap for vq: 1 ring_phys: 0 ring_size: 1028
> Checking vq: 2 ring_phys: ed000 ring_size: 5124 >>>>>>>>>>>>>>>>>>.
> Calling l: 5124 for start_addr: c9000 for vq 2
>
> and the ROM between 0xf0000 and 0xfffff, which no ring overlaps with:
>
> vhost_set_memory: section: 0x7fe2801f2aa0 section->size: 65536 add: 1
> Before vhost_verify_ring_mappings: start_addr: f0000 size: 65536
> Checking vq: 0 ring_phys: 0 ring_size: 1028 >>>>>>>>>>>>>>>>>>.
> Got ranges_overlap for vq: 0 ring_phys: 0 ring_size: 1028
> Checking vq: 1 ring_phys: 0 ring_size: 1028 >>>>>>>>>>>>>>>>>>.
> Got ranges_overlap for vq: 1 ring_phys: 0 ring_size: 1028
> Checking vq: 2 ring_phys: ed000 ring_size: 5124 >>>>>>>>>>>>>>>>>>.
> Got ranges_overlap for vq: 2 ring_phys: ed000 ring_size: 5124
>
>
>
> SeaBIOS is indeed not initializing vqs 0/1 (the control and event
> queues), so their ring_phys is 0. But the one that is failing is vq 2,
> the first request queue.
>
> Your patch seems good, but shouldn't fix this problem.
>
> Paolo
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