Re: [Qemu-devel] [PULL V3 00/20] Net patches

[Dmitry Fleytman]

> On 27 May 2016, at 06:35 AM, Jason Wang <address@hidden> wrote:
> 
> 
> 
> On 2016年05月26日 23:08, Peter Maydell wrote:
>> On 26 May 2016 at 03:16, Jason Wang <address@hidden> wrote:
>>> The following changes since commit 287db79df8af8e31f18e262feb5e05103a09e4d4:
>>> 
>>>   Merge remote-tracking branch 'remotes/ehabkost/tags/x86-pull-request' 
>>> into staging (2016-05-24 13:06:33 +0100)
>>> 
>>> are available in the git repository at:
>>> 
>>>   https://github.com/jasowang/qemu.git tags/net-pull-request
>>> 
>>> for you to fetch changes up to 136796b070ddd09dd14ef73e77ae20419ba6554a:
>>> 
>>>   net/net: Add SocketReadState for reuse codes (2016-05-26 09:58:22 +0800)
>>> 
>>> ----------------------------------------------------------------
>>> 
>>> Main changes:
>>> - e1000e emulation
>>> - convet vmxnet3 to use DMA api
>>> Changes from V2:
>>> - fix clang build
>>> Changes from V1:
>>> - fix 32bit build
>> Hi. I'm afraid this introduces new errors in the clang sanitizer output
>> from make check: all the check-qtest-i386 and check-qtest-x86_64
>> runs produce output like:
>> 
>> /home/petmay01/linaro/qemu-for-merges/hw/pci/pcie.c:641:25: runtime
>> error: left shift of 4092 by 20 places cannot be
>>  represented in type 'int'
>> /home/petmay01/linaro/qemu-for-merges/hw/pci/pcie.c:642:45: runtime
>> error: left shift of 4092 by 20 places cannot be
>>  represented in type 'int'
>> ==14902==WARNING: Trying to symbolize code, but external symbolizer is
>> not initialized!
>> /home/petmay01/linaro/qemu-for-merges/include/qemu/bswap.h:120:1:
>> runtime error: store to misaligned address 0x2b23c01e6674 for type
>> 'uint64_t' (aka 'unsigned long'), which requires 8 byte alignment
>> 0x2b23c01e6674: note: pointer points here
>>   03 00 01 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00
>> 00 00  00 00 00 00 00 00 00 00
>>               ^
> 
> Sorry for the trouble again. Wonder the correct way to enable sanitizer, 
> after I add "-fsanitizer=address", it produces tons of warnings and errors 
> but don't find the above outputs.
> 
>> The stuff about left shifts is just the usual shift-into-sign-bit
>> which we haven't yet sorted out what we're doing with (ie
>> whether we can ignore them and shut up the sanitizer without
>> silencing other interesting warnings), but we shouldn't be doing
>> misaligned stores of 64-bit values.
> 
> I agree.
> 
>> 
>> Apologies for the lack of any backtraces in the output, but
>> this is almost certainly the result of trying to do le64_to_cpu()
>> or cpu_to_le64() on a buffer which isn't necessarily aligned
>> (usually some pointer into guest memory). Use the functions
>> ldq_le_p() and stq_le_p() instead, which will handle a
>> potentially misaligned pointer for you. (There are similar
>> functions for other access widths too.)
>> 
>> thanks
>> -- PMM
> 
> Leonid and Dmitry, please check the guest memory access as suggested above 
> and respin the series. I will hold the pull until the new version.

Hi Peter,

It turned out that the issue is not in the new code but in pci.h helper 
functions used by the new code to fill DSN capability.

Following patch fixes the problem:

diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index ef6ba51..ee238ad
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -468,13 +468,13 @@ pci_get_long(const uint8_t *config)
 static inline void
 pci_set_quad(uint8_t *config, uint64_t val)
 {
-    cpu_to_le64w((uint64_t *)config, val);
+    stq_le_p(config, val);
 }

 static inline uint64_t
 pci_get_quad(const uint8_t *config)
 {
-    return le64_to_cpup((const uint64_t *)config);
+    return ldq_le_p(config);
 }

I see from git blame that some time ago you did similar change in all other
pci_set_* pci_get_* functions except these two.

Is there any specific reason you did not change these two functions then?

Thanks,
Dmitry

> 
> Thanks
> 
>