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Re: [RFC PATCH-for-5.2] hw/s390x/pci: Fix endianness issue
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [RFC PATCH-for-5.2] hw/s390x/pci: Fix endianness issue |
Date: |
Tue, 17 Nov 2020 14:12:00 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 |
On 11/17/20 2:00 PM, Peter Maydell wrote:
> On Tue, 17 Nov 2020 at 12:03, Philippe Mathieu-Daudé <philmd@redhat.com>
> wrote:
>>
>> Fix an endianness issue reported by Cornelia:
>>
>>> s390x tcg guest on x86, virtio-pci devices are not detected. The
>>> relevant feature bits are visible to the guest. Same breakage with
>>> different guest kernels.
>>> KVM guests and s390x tcg guests on s390x are fine.
>>
>> Fixes: 28dc86a0729 ("s390x/pci: use a PCI Group structure")
>> Reported-by: Cornelia Huck <cohuck@redhat.com>
>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>> ---
>> RFC because review-only patch, untested
>> ---
>> hw/s390x/s390-pci-inst.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/hw/s390x/s390-pci-inst.c b/hw/s390x/s390-pci-inst.c
>> index 58cd041d17f..cfb54b4d8ec 100644
>> --- a/hw/s390x/s390-pci-inst.c
>> +++ b/hw/s390x/s390-pci-inst.c
>> @@ -305,7 +305,7 @@ int clp_service_call(S390CPU *cpu, uint8_t r2, uintptr_t
>> ra)
>> ClpReqQueryPciGrp *reqgrp = (ClpReqQueryPciGrp *)reqh;
>> S390PCIGroup *group;
>>
>> - group = s390_group_find(reqgrp->g);
>> + group = s390_group_find(ldl_p(&reqgrp->g));
>
> 'g' in the ClpReqQueryPciGrp struct is a uint32_t, so
> adding the ldl_p() will have no effect unless (a) the
> structure is not 4-aligned and (b) the host will fault on
> unaligned accesses, which isn't the case for x86 hosts.
>
> Q: is this struct really in host order, or should we
> be using ldl_le_p() or ldl_be_p() and friends here and
> elsewhere?
Now than I had lunch, your comment is obvious...
IIUC we should use ldl_le_p() here and fix all the other
uses.
>
> thanks
> -- PMM
>
- [RFC PATCH-for-5.2] hw/s390x/pci: Fix endianness issue, Philippe Mathieu-Daudé, 2020/11/17
- Re: [RFC PATCH-for-5.2] hw/s390x/pci: Fix endianness issue, Cornelia Huck, 2020/11/17
- Re: [RFC PATCH-for-5.2] hw/s390x/pci: Fix endianness issue, Peter Maydell, 2020/11/17
- Re: [RFC PATCH-for-5.2] hw/s390x/pci: Fix endianness issue,
Philippe Mathieu-Daudé <=
- Re: [RFC PATCH-for-5.2] hw/s390x/pci: Fix endianness issue, Pierre Morel, 2020/11/17
- Re: [RFC PATCH-for-5.2] hw/s390x/pci: Fix endianness issue, Cornelia Huck, 2020/11/17
- Re: [RFC PATCH-for-5.2] hw/s390x/pci: Fix endianness issue, Matthew Rosato, 2020/11/17
- Re: [RFC PATCH-for-5.2] hw/s390x/pci: Fix endianness issue, Cornelia Huck, 2020/11/17
- Re: [RFC PATCH-for-5.2] hw/s390x/pci: Fix endianness issue, Matthew Rosato, 2020/11/17
- Re: [RFC PATCH-for-5.2] hw/s390x/pci: Fix endianness issue, Cornelia Huck, 2020/11/17
- Re: [RFC PATCH-for-5.2] hw/s390x/pci: Fix endianness issue, Matthew Rosato, 2020/11/17
- Re: [RFC PATCH-for-5.2] hw/s390x/pci: Fix endianness issue, Cornelia Huck, 2020/11/17
- Re: [RFC PATCH-for-5.2] hw/s390x/pci: Fix endianness issue, Thomas Huth, 2020/11/17