Messages in this thread Patch in this message | | | Date | Tue, 7 Sep 2010 18:01:48 -0600 | Subject | Re: [Qemu-devel] [solved] Guest cannot handle a PCI BAR > 1GB | From | Cam Macdonell <> |
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It seems it was the alignment value being passed back from pci_resource_alignment(). The return type is an int, which was causing value of 2GB to be sign extended to to 0xffffffff80000000. Changing the return type to resource_size_t allows BAR values >= 2GB to be successfully assigned.
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index 679c39d..3d23522 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -318,7 +318,7 @@ static inline int pci_ats_enabled(struct pci_dev *dev) } #endif /* CONFIG_PCI_IOV */
-static inline int pci_resource_alignment(struct pci_dev *dev, +static inline resource_size_t pci_resource_alignment(struct pci_dev *dev, struct resource *res) { #ifdef CONFIG_PCI_IOV
On Mon, Sep 6, 2010 at 11:24 AM, Cam Macdonell <cam@cs.ualberta.ca> wrote: > On Mon, Sep 6, 2010 at 10:37 AM, Cam Macdonell <cam@cs.ualberta.ca> wrote: >> >> >> On Sun, Sep 5, 2010 at 10:50 AM, Avi Kivity <avi@redhat.com> wrote: >>> >>> On 09/04/2010 01:22 AM, Cam Macdonell wrote: >>>> >>>> Hi, >>>> >>>> I'm trying to test 2 GB (and eventually larger) BARs with ivshmem and >>>> I get an error in the guest that it is able to find a mem resource for >>>> a BAR larger than 1GB. I'm using 64-bit BARs. >>>> >>>> when running with 6GB of RAM and a 1GB BAR for ivshmem, it finds a >>>> resource (and searches beyond 32-bit values to find it). Here is a >>>> log from printfs added to the loop that searches the resources from >>>> find_resource() in kernel/resource.c:363. >>>> >>> >>> This is a kernel question, not a qemu issue. Copying lkml. >>> >>>> trying 'tmp.start' 1000 to >>>> 'tmp.end' fff >>>> trying 'tmp.start' 9f400 to >>>> 'tmp.end' 9f3ff >>>> trying 'tmp.start' a0000 to >>>> 'tmp.end' effff >>>> trying 'tmp.start' 100000 to >>>> 'tmp.end' fffff >>>> trying 'tmp.start' dfffd000 to >>>> 'tmp.end' dfffcfff >>>> trying 'tmp.start' e0000000 to >>>> 'tmp.end' efffffff >>>> trying 'tmp.start' f2000000 to >>>> 'tmp.end' f1ffffff >>>> trying 'tmp.start' f2001000 to >>>> 'tmp.end' f200ffff >>>> trying 'tmp.start' f2020000 to >>>> 'tmp.end' f201ffff >>>> trying 'tmp.start' f2021000 to >>>> 'tmp.end' f202ffff >>>> trying 'tmp.start' f2040000 to >>>> 'tmp.end' f203ffff >>>> trying 'tmp.start' f2040100 to >>>> 'tmp.end' febfffff >>>> trying 'tmp.start' fec00400 to >>>> 'tmp.end' fffbffff >>>> trying 'tmp.start' 100000000 to >>>> 'tmp.end' ffffffff >>>> trying 'tmp.start' 1a0000000 to >>>> 'tmp.end' ffffffffffffffff >>>> pci 0000:00:04.0: BAR 2: assigned [mem 0x1c0000000-0x1ffffffff 64bit] >>>> pci 0000:00:04.0: BAR 2: set to [mem 0x1c0000000-0x1ffffffff 64bit] >>>> (PCI address [0x1c0000000-0x1ffffffff] >>>> >>>> and you can see the BAR is successfully assigned. >>>> >>>> However, with a 2GB BAR (below), the search fails, but it also never >>>> searches beyong 32-bits. Again, all that's changed is the size of the >>>> ivshmem region. >>>> >>>> trying 'tmp.start' 1000 to >>>> 'tmp.end' fff >>>> trying 'tmp.start' 9f400 to >>>> 'tmp.end' 9f3ff >>>> trying 'tmp.start' a0000 to >>>> 'tmp.end' effff >>>> trying 'tmp.start' 100000 to >>>> 'tmp.end' fffff >>>> trying 'tmp.start' dfffd000 to >>>> 'tmp.end' dfffcfff >>>> pci 0000:00:04.0: BAR 2: can't assign mem (size 0x80000000) >>>> >>>> Is there a limit to PCI BAR sizes or resources? Any pointers or >>>> further debugging tips are greatly appreciated. >>>> >>> >>> What kernel version are you looking at? >> >> latest kvm git, 2.6.36-rc2+ >> >>> >>> Please add printks to the loop so we can see this->start and this->end. It smells like a truncation issue. >> >> Success with a 1GB BAR >> this->start 1000, this->end 9f3ff >> this->start 9f400, this->end 9ffff >> this->start f0000, this->end fffff >> this->start 100000, this->end dfffcfff >> this->start dfffd000, this->end dfffffff >> this->start f0000000, this->end f1ffffff >> this->start f2000000, this->end f2000fff >> this->start f2010000, this->end f201ffff >> this->start f2020000, this->end f2020fff >> this->start f2030000, this->end f203ffff >> this->start f2040000, this->end f20400ff >> this->start fec00000, this->end fec003ff >> this->start fffc0000, this->end ffffffff >> this->start 100000000, this->end 11fffffff >> tmp.start 120000000, tmp.end ffffffffffffffff >> pci 0000:00:04.0: BAR 2: assigned [mem 0x140000000-0x17fffffff 64bit] >> and when it fails with a 2GB BAR, the following is printed >> this->start 1000, this->end 9f3ff >> this->start 9f400, this->end 9ffff >> this->start f0000, this->end fffff >> this->start 100000, this->end dfffcfff >> this->start dfffd000, this->end dfffffff >> pci 0000:00:04.0: BAR 2: can't assign mem (size 0x80000000) >> I added a few more debug statements and found that in the failure case, the function returns that it found a region (the last one printed before the error). I've added printfs for the two tests in the if that determine when a region is found: >> if (tmp.start < tmp.end && tmp.end - tmp.start >= size - 1) { >> new->start = tmp.start; >> new->end = tmp.start + size - 1; >> printk(KERN_INFO "returning 0\n"); >> return 0; >> } >> this->start 1000, this->end 9f3ff >> tmp.start 80000000, tmp.end fff >> true: ffffffff80000fff >= 7fffffff >> this->start 9f400, this->end 9ffff >> tmp.start 80000000, tmp.end 9f3ff >> true: ffffffff8009f3ff >= 7fffffff >> this->start f0000, this->end fffff >> tmp.start 80000000, tmp.end effff >> true: ffffffff800effff >= 7fffffff >> this->start 100000, this->end dfffcfff >> tmp.start 80000000, tmp.end fffff >> true: ffffffff800fffff >= 7fffffff >> this->start dfffd000, this->end dfffffff >> tmp.start 100000, tmp.end dfffcfff >> true: 100000 < dfffcfff >> true: dfefcfff >= 7fffffff >> returning 0 >> pci 0000:00:04.0: BAR 2: can't assign mem (size 0x80000000) > > Further to this, it seems tmp.start is getting set to zero by the ALIGN macro > > 2GB BAR: > this->start dfffd000, this->end dfffffff > tmp.start dfffd000 > tmp.start 0 > tmp.start 100000, tmp.end dfffcfff > > 1GB BAR: > this->start dfffd000, this->end dfffffff > tmp.start dfffd000 > tmp.start 100000000 > tmp.start 100000000, tmp.end dfffcfff > > I'll dig into the ALIGN macro. > >> >> >> >> >>> >>> -- >>> error compiling committee.c: too many arguments to function >>> >> > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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