[Bug 115451] New: memset hang on pci device memory using kvm

[Bug 115451] New: memset hang on pci device memory using kvm

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=115451

            Bug ID: 115451
           Summary: memset hang on pci device memory using kvm
           Product: Virtualization
           Version: unspecified
    Kernel Version: RHEL - 2.6.18-308.el5
          Hardware: Intel
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: high
          Priority: P1
         Component: kvm
          Assignee: virtualization_kvm@kernel-bugs.osdl.org
          Reporter: gauravs.2010@gmail.com
        Regression: No

i have host x86 based rhel system [kernel version - 2.6.18-308.el5]. On this I
am trying to boot up a debian amd64 image using qemu with kvm.

On my virtual os i have a pcimem application, through which I R/W any
configured memory on pci devices.
Issue is whenever i try to use memset in excess of 156 bytes in my pcimem
application to configure any pci device memory, call to memset hangs. 
However, memcpy work fine in all scenarios.

memset works fine if boot my virtual os without kvm.


my kvm version is :
$/usr/libexec/qemu-kvm --help
QEMU PC emulator version 0.9.1 (kvm-83-maint-snapshot-20090205), Copyright (c)
2003-2008 Fabrice Bellard

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[Bug 115451] memset hang on pci device memory using kvm

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https://bugzilla.kernel.org/show_bug.cgi?id=115451

Huaitong Han <oenhan@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |oenhan@gmail.com

--- Comment #1 from Huaitong Han <oenhan@gmail.com> ---
You should try reproduce it on upstream kernel, and list steps if it can be
reproduced, so that many people can help to debug it.

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[Bug 115451] memset hang on pci device memory using kvm

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https://bugzilla.kernel.org/show_bug.cgi?id=115451

--- Comment #2 from Gaurav Sharma <gauravs.2010@gmail.com> ---
Following is the system info :
Host machine kernel version : 2.6.18-308.el5
Guest OS : Debian 3.2.0-4-686-pae
KVM vesrion : QEMU PC emulator version 0.9.1

Following are the steps to re-create the issue :
1. Boot the guest OS using QEMU with KVM enabled.
2. lspci will list down the pci devices configured on the guest OS.
3. I have a some PCI device configured with bar0 memory.
4. modify the pcimem.c application to use call memset

// This code is being modified to call memset to do a bulk write transaction
case 'w':
         fprintf(stderr, "Before doing memset\n");
         memset((virt_addr), 1, datalen);
         fprintf(stderr, "after doing memset\n");
         break;

5. Call the pcimem application to write on bar0 memory.
6. It results in memset call in hang, and the application needs to be
explicitly killed. I do not get the log message after memset call.

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[Bug 115451] memset hang on pci device memory using kvm

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=115451

--- Comment #3 from Gaurav Sharma <gauravs.2010@gmail.com> ---
Created attachment 211901
  --> https://bugzilla.kernel.org/attachment.cgi?id=211901&action=edit
Attached is the pcimem application that i use

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[Bug 115451] memset hang on pci device memory using kvm

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https://bugzilla.kernel.org/show_bug.cgi?id=115451

--- Comment #4 from Gaurav Sharma <gauravs.2010@gmail.com> ---
Also, when memset fails, i get following from dmesg on host machine :
emulation failed (pagetable) rip 410bab 66 0f 7f 07
emulation failed (pagetable) rip 410bab 66 0f 7f 07
emulation failed (pagetable) rip 410bab 66 0f 7f 07
emulation failed (pagetable) rip 410bab 66 0f 7f 07

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[Bug 115451] memset hang on pci device memory using kvm

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=115451

Paolo Bonzini <bonzini@gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bonzini@gnu.org

--- Comment #5 from Paolo Bonzini <bonzini@gnu.org> ---
Please try on KVM and QEMU version that are less than 7 years old...

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[Bug 115451] memset hang on pci device memory using kvm

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=115451

--- Comment #6 from Gaurav Sharma <gauravs.2010@gmail.com> ---
I am using qemu version 2.2.0 and kvm modules are the default with the host
kernel version [RHEL 5.8], which doesn't seems to be that old to me.
Any data point am i missing ?

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[Bug 115451] memset hang on pci device memory using kvm

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https://bugzilla.kernel.org/show_bug.cgi?id=115451

--- Comment #7 from Paolo Bonzini <bonzini@gnu.org> ---
First, RHEL5.8 was released in February 2012, which is 4 years old.  The latest
RHEL release is 5.11 (September 2014).  Second, RHEL5's KVM modules were forked
from the upstream kernel around 2009.  It hasn't had any features added for at
least 5 years.

In any case, this bug tracker is only for the upstream kernel.  Even if the bug
was identified and fixed, you would have to open a support case with Red Hat to
get it in the distribution---and you would probably get it only in RHEL7, or at
most (quite unlikely) in RHEL6, because RHEL5 only has major security fixes
applied at this point in time.

Anyway, from comment 4, it looks like RHEL5 doesn't have support for SSE
instructions (movdqa in this case) to and from PCI BARs.  This is supported in
upstream since April 2012 (generic support for SSE came in March 2011, while
movdqa was added one year later).

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[Bug 115451] memset hang on pci device memory using kvm

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https://bugzilla.kernel.org/show_bug.cgi?id=115451

Paolo Bonzini <bonzini@gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |PATCH_ALREADY_AVAILABLE

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