- 02 Aug, 2010 22 commits
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Vivek Natarajan authored
commit 3a374952 upstream. If bit 29 is set, MAC H/W can attempt to decrypt the received aggregate with WEP or TKIP, eventhough the received frame may be a CRC failed corrupted frame. If this bit is set, H/W obeys key type in keycache. If it is not set and if the key type in keycache is neither open nor AES, H/W forces key type to be open. But bit 29 should be set to 1 for AsyncFIFO feature to encrypt/decrypt the aggregate with WEP or TKIP. Reported-by:
Johan Hovold <johan.hovold@lundinova.se> Signed-off-by:
Vivek Natarajan <vnatarajan@atheros.com> Signed-off-by:
Ranga Rao Ravuri <ranga.ravuri@atheros.com> Signed-off-by:
John W. Linville <linville@tuxdriver.com> Signed-off-by:
Greg Kroah-Hartman <gregkh@suse.de>
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Luis R. Rodriguez authored
commit 14acdde6 upstream. The newer single chip hardware family of chipsets have not been experiencing issues with power saving set by default with recent fixes merged (even into stable). The remaining issues are only reported with AR5416 and since enabling PS by default can increase power savings considerably best to take advantage of that feature as this has been tested properly. For more details on this issue see the bug report: http://bugzilla.kernel.org/show_bug.cgi?id=14267 We leave AR5416 with PS disabled by default, that seems to require some more work. Cc: Peter Stuge <peter@stuge.se> Cc: Justin P. Mattock <justinmattock@gmail.com> Cc: Kristoffer Ericson <kristoffer.ericson@gmail.com> Signed-off-by:
Luis R. Rodriguez <lrodriguez@atheros.com> Signed-off-by:
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Luis R. Rodriguez authored
commit 9637e516 upstream. Jumbo frames are not supported, and if they are seen it is likely a bogus frame so just silently discard them instead of warning on them all time. Also, instead of dropping them immediately though move the check *after* we check for all sort of frame errors. This should enable us to discard these frames if the hardware picks other bogus items first. Lets see if we still get those jumbo counters increasing still with this. Jumbo frames would happen if we tell hardware we can support a small 802.11 chunks of DMA'd frame, hardware would split RX'd frames into parts and we'd have to reconstruct them in software. This is done with USB due to the bulk size but with ath5k we already provide a good limit to hardware and this should not be happening. This is reported quite often and if it fills the logs then this needs to be addressed and to avoid spurious reports. Signed-off-by:
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Trond Myklebust authored
commit b76ce561 upstream. If the attempt to read the calldir fails, then instead of storing the read bytes, we currently discard them. This leads to a garbage final result when upon re-entry to the same routine, we read the remaining bytes. Fixes the regression in bugzilla number 16213. Please see https://bugzilla.kernel.org/show_bug.cgi?id=16213Signed-off-by:
Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by:
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Trond Myklebust authored
commit 0be8189f upstream. Currently, we do not display the minor version mount parameter in the /proc mount info. Signed-off-by:
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Trond Myklebust authored
commit d3f6baaa upstream. Apparently, we have never been able to set the atime correctly from the NFSv4 client. Reported-by:
小倉一夫 <ka-ogura@bd6.so-net.ne.jp> Signed-off-by:
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Mikael Pettersson authored
commit f8324e20 upstream. The kernel's math-emu code contains a macro _FP_FROM_INT() which is used to convert an integer to a raw normalized floating-point value. It does this basically in three steps: 1. Compute the exponent from the number of leading zero bits. 2. Downshift large fractions to put the MSB in the right position for normalized fractions. 3. Upshift small fractions to put the MSB in the right position. There is an boundary error in step 2, causing a fraction with its MSB exactly one bit above the normalized MSB position to not be downshifted. This results in a non-normalized raw float, which when packed becomes a massively inaccurate representation for that input. The impact of this depends on a number of arch-specific factors, but it is known to have broken emulation of FXTOD instructions on UltraSPARC III, which was originally reported as GCC bug 44631 <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44631>. Any arch which uses math-emu to emulate conversions from integers to same-size floats may be affected. The fix is simple: the exponent comparison used to determine if the fraction should be downshifted must be "<=" not "<". I'm sending a kernel module to test this as a reply to this message. There are also SPARC user-space test cases in the GCC bug entry. Signed-off-by:
Mikael Pettersson <mikpe@it.uu.se> Signed-off-by:
David S. Miller <davem@davemloft.net> Signed-off-by:
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Rob Landley authored
commit 7469a9ac upstream. Signed-off-by:
Rob Landley <rob@landley.net> Signed-off-by:
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Alexander Duyck authored
commit 22896639 upstream. This patch allows us to treat the alternate mac address as though it is the physical address on the adapter. This is accomplished by letting the alt_mac_address function to only fail on an NVM error. If no errors occur and the alternate mac address is not present then RAR0 is read as the default mac address. Signed-off-by:
Alexander Duyck <alexander.h.duyck@intel.com> Signed-off-by:
Jeff Kirsher <jeffrey.t.kirsher@intel.com> Signed-off-by:
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Brandon Philips authored
commit 38000a94 upstream. sky2_phy_reinit is called by the ethtool helpers sky2_set_settings, sky2_nway_reset and sky2_set_pauseparam when netif_running. However, at the end of sky2_phy_init GM_GP_CTRL has GM_GPCR_RX_ENA and GM_GPCR_TX_ENA cleared. So, doing these commands causes the device to stop working: $ ethtool -r eth0 $ ethtool -A eth0 autoneg off Fix this issue by enabling Rx/Tx after running sky2_phy_init in sky2_phy_reinit. Signed-off-by:
Brandon Philips <bphilips@suse.de> Tested-by:
Mike McCormack <mikem@ring3k.org> Signed-off-by:
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Florian Fainelli authored
commit ed770f01 upstream. If the call to phy_connect fails, we will return directly instead of freeing the previously allocated struct net_device. Signed-off-by:
Florian Fainelli <florian@openwrt.org> Signed-off-by:
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Luke Yelavich authored
commit 3bfea98f upstream. BugLink: https://bugs.launchpad.net/bugs/463178 Set Macbook 5,2 (106b:4a00) hardware to use ALC885_MB5 Signed-off-by:
Luke Yelavich <luke.yelavich@canonical.com> Signed-off-by:
Takashi Iwai <tiwai@suse.de> Signed-off-by:
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David Howells authored
commit 4c0c03ca upstream. Fix the security problem in the CIFS filesystem DNS lookup code in which a malicious redirect could be installed by a random user by simply adding a result record into one of their keyrings with add_key() and then invoking a CIFS CFS lookup [CVE-2010-2524]. This is done by creating an internal keyring specifically for the caching of DNS lookups. To enforce the use of this keyring, the module init routine creates a set of override credentials with the keyring installed as the thread keyring and instructs request_key() to only install lookup result keys in that keyring. The override is then applied around the call to request_key(). This has some additional benefits when a kernel service uses this module to request a key: (1) The result keys are owned by root, not the user that caused the lookup. (2) The result keys don't pop up in the user's keyrings. (3) The result keys don't come out of the quota of the user that caused the lookup. The keyring can be viewed as root by doing cat /proc/keys: 2a0ca6c3 I----- 1 perm 1f030000 0 0 keyring .dns_resolver: 1/4 It can then be listed with 'keyctl list' by root. # keyctl list 0x2a0ca6c3 1 key in keyring: 726766307: --alswrv 0 0 dns_resolver: foo.bar.com Signed-off-by:
David Howells <dhowells@redhat.com> Reviewed-and-Tested-by:
Jeff Layton <jlayton@redhat.com> Acked-by:
Steve French <smfrench@gmail.com> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by:
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Jeff Layton authored
commit ed0e3ace upstream. Busy-file renames don't actually work across directories, so we need to limit this code to renames within the same dir. This fixes the bug detailed here: https://bugzilla.redhat.com/show_bug.cgi?id=591938Signed-off-by:
Steve French <sfrench@us.ibm.com> Signed-off-by:
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Jeff Layton authored
commit 8a224d48 upstream. This bug appears to be the result of a cut-and-paste mistake from the NTLMv1 code. The function to generate the MAC key was commented out, but not the conditional above it. The conditional then ended up causing the session setup key not to be copied to the buffer unless this was the first session on the socket, and that made all but the first NTLMv2 session setup fail. Fix this by removing the conditional and all of the commented clutter that made it difficult to see. Reported-by:
Gunther Deschner <gdeschne@redhat.com> Signed-off-by:
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Jean Delvare authored
commit 436cad2a upstream. The IT8720F has no VIN7 pin, so VCCH should always be routed internally to VIN7 with an internal divider. Curiously, there still is a configuration bit to control this, which means it can be set incorrectly. And even more curiously, many boards out there are improperly configured, even though the IT8720F datasheet claims that the internal routing of VCCH to VIN7 is the default setting. So we force the internal routing in this case. It turns out that all boards with the wrong setting are from Gigabyte, so I suspect a BIOS bug. But it's easy enough to workaround in the driver, so let's do it. Signed-off-by:
Jean Delvare <khali@linux-fr.org> Cc: Jean-Marc Spaggiari <jean-marc@spaggiari.org> Signed-off-by:
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Jean Delvare authored
commit d883b9f0 upstream. On hyper-threaded CPUs, each core appears twice in the CPU list. Skip the second entry to avoid duplicate sensors. Signed-off-by:
Huaxu Wan <huaxu.wan@intel.com> Signed-off-by:
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Jean Delvare authored
commit 3f4f09b4 upstream. Don't assume that CPU entry number and core ID always match. It worked in the simple cases (single CPU, no HT) but fails on multi-CPU systems. Signed-off-by:
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Andreas Herrmann authored
commit d535bad9 upstream. Reported temperature for ASB1 CPUs is too high. Add ASB1 CPU revisions (these are also non-desktop variants) to the list of CPUs for which the temperature fixup is not required. Example: (from LENOVO ThinkPad Edge 13, 01972NG, system was idle) Current kernel reports $ sensors k8temp-pci-00c3 Adapter: PCI adapter Core0 Temp: +74.0 C Core0 Temp: +70.0 C Core1 Temp: +69.0 C Core1 Temp: +70.0 C With this patch I have $ sensors k8temp-pci-00c3 Adapter: PCI adapter Core0 Temp: +54.0 C Core0 Temp: +51.0 C Core1 Temp: +48.0 C Core1 Temp: +49.0 C Cc: Rudolf Marek <r.marek@assembler.cz> Signed-off-by:
Andreas Herrmann <andreas.herrmann3@amd.com> Signed-off-by:
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Jean Delvare authored
commit cd4de21f upstream. Commit a2e066bb introduced core swapping for CPU models 64 and later. I recently had a report about a Sempron 3200+, model 95, for which this patch broke temperature reading. It happens that this is a single-core processor, so the effect of the swapping was to read a temperature value for a core that didn't exist, leading to an incorrect value (-49 degrees C.) Disabling core swapping on singe-core processors should fix this. Additional comment from Andreas: The BKDG says Thermal Sensor Core Select (ThermSenseCoreSel)-Bit 2. This bit selects the CPU whose temperature is reported in the CurTemp field. This bit only applies to dual core processors. For single core processors CPU0 Thermal Sensor is always selected. k8temp_probe() correctly detected that SEL_CORE can't be used on single core CPU. Thus k8temp did never update the temperature values stored in temp[1][x] and -49 degrees was reported. For single core CPUs we must use the values read into temp[0][x]. Signed-off-by:
Rick Moritz <rhavin@gmx.net> Acked-by:
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Christoph Fritz authored
For some Netbook computers with Broadcom BCM4312 wireless interfaces, the SPROM has been moved to a new location. When the ssb driver tries to read the old location, the systems hangs when trying to read a non-existent location. Such freezes are particularly bad as they do not log the failure. This patch is modified from commit da1fdb02 with some pieces from other mainline changes so that it can be applied to stable 2.6.34.Y. Signed-off-by:
Larry Finger <Larry.Finger@lwfinger.net> Signed-off-by:
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Michael S. Tsirkin authored
commit b03214d5 upstream. virtio-pci resets the device at startup by writing to the status register, but this does not clear the pci config space, specifically msi enable status which affects register layout. This breaks things like kdump when they try to use e.g. virtio-blk. Fix by forcing msi off at startup. Since pci.c already has a routine to do this, we export and use it instead of duplicating code. Signed-off-by:
Michael S. Tsirkin <mst@redhat.com> Tested-by:
Vivek Goyal <vgoyal@redhat.com> Acked-by:
Jesse Barnes <jbarnes@virtuousgeek.org> Cc: linux-pci@vger.kernel.org Signed-off-by:
Rusty Russell <rusty@rustcorp.com.au> Signed-off-by:
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- 05 Jul, 2010 18 commits
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Greg Kroah-Hartman authored
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Wei Yongjun authored
commit 2e3219b5 upstream. commit 5fa782c2 sctp: Fix skb_over_panic resulting from multiple invalid \ parameter errors (CVE-2010-1173) (v4) cause 'error cause' never be add the the ERROR chunk due to some typo when check valid length in sctp_init_cause_fixed(). Signed-off-by:
Wei Yongjun <yjwei@cn.fujitsu.com> Reviewed-by:
Neil Horman <nhorman@tuxdriver.com> Acked-by:
Vlad Yasevich <vladislav.yasevich@hp.com> Signed-off-by:
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Ben Hutchings authored
commit 6377a7ae upstream. On specific platforms, MSI is unreliable on some of the QLA24xx chips, resulting in fatal I/O errors under load, as reported in <http://bugs.debian.org/572322> and by some RHEL customers. Signed-off-by:
Giridhar Malavali <giridhar.malavali@qlogic.com> Signed-off-by:
James Bottomley <James.Bottomley@suse.de> Cc: Ben Hutchings <ben@decadent.org.uk> Signed-off-by:
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Toshiyuki Okajima authored
commit cea7daa3 upstream. find_keyring_by_name() can gain access to a keyring that has had its reference count reduced to zero, and is thus ready to be freed. This then allows the dead keyring to be brought back into use whilst it is being destroyed. The following timeline illustrates the process: |(cleaner) (user) | | free_user(user) sys_keyctl() | | | | key_put(user->session_keyring) keyctl_get_keyring_ID() | || //=> keyring->usage = 0 | | |schedule_work(&key_cleanup_task) lookup_user_key() | || | | kmem_cache_free(,user) | | . |[KEY_SPEC_USER_KEYRING] | . install_user_keyrings() | . || | key_cleanup() [<= worker_thread()] || | | || | [spin_lock(&key_serial_lock)] |[mutex_lock(&key_user_keyr..mutex)] | | || | atomic_read() == 0 || | |{ rb_ease(&key->serial_node,) } || | | || | [spin_unlock(&key_serial_lock)] |find_keyring_by_name() | | ||| | keyring_destroy(keyring) ||[read_lock(&keyring_name_lock)] | || ||| | |[write_lock(&keyring_name_lock)] ||atomic_inc(&keyring->usage) | |. ||| *** GET freeing keyring *** | |. ||[read_unlock(&keyring_name_lock)] | || || | |list_del() |[mutex_unlock(&key_user_k..mutex)] | || | | |[write_unlock(&keyring_name_lock)] ** INVALID keyring is returned ** | | . | kmem_cache_free(,keyring) . | . | atomic_dec(&keyring->usage) v *** DESTROYED *** TIME If CONFIG_SLUB_DEBUG=y then we may see the following message generated: ============================================================================= BUG key_jar: Poison overwritten ----------------------------------------------------------------------------- INFO: 0xffff880197a7e200-0xffff880197a7e200. First byte 0x6a instead of 0x6b INFO: Allocated in key_alloc+0x10b/0x35f age=25 cpu=1 pid=5086 INFO: Freed in key_cleanup+0xd0/0xd5 age=12 cpu=1 pid=10 INFO: Slab 0xffffea000592cb90 objects=16 used=2 fp=0xffff880197a7e200 flags=0x200000000000c3 INFO: Object 0xffff880197a7e200 @offset=512 fp=0xffff880197a7e300 Bytes b4 0xffff880197a7e1f0: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZZZZZ Object 0xffff880197a7e200: 6a 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b jkkkkkkkkkkkkkkk Alternatively, we may see a system panic happen, such as: BUG: unable to handle kernel NULL pointer dereference at 0000000000000001 IP: [<ffffffff810e61a3>] kmem_cache_alloc+0x5b/0xe9 PGD 6b2b4067 PUD 6a80d067 PMD 0 Oops: 0000 [#1] SMP last sysfs file: /sys/kernel/kexec_crash_loaded CPU 1 ... Pid: 31245, comm: su Not tainted 2.6.34-rc5-nofixed-nodebug #2 D2089/PRIMERGY RIP: 0010:[<ffffffff810e61a3>] [<ffffffff810e61a3>] kmem_cache_alloc+0x5b/0xe9 RSP: 0018:ffff88006af3bd98 EFLAGS: 00010002 RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff88007d19900b RDX: 0000000100000000 RSI: 00000000000080d0 RDI: ffffffff81828430 RBP: ffffffff81828430 R08: ffff88000a293750 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000100000 R12: 00000000000080d0 R13: 00000000000080d0 R14: 0000000000000296 R15: ffffffff810f20ce FS: 00007f97116bc700(0000) GS:ffff88000a280000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000001 CR3: 000000006a91c000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process su (pid: 31245, threadinfo ffff88006af3a000, task ffff8800374414c0) Stack: 0000000512e0958e 0000000000008000 ffff880037f8d180 0000000000000001 0000000000000000 0000000000008001 ffff88007d199000 ffffffff810f20ce 0000000000008000 ffff88006af3be48 0000000000000024 ffffffff810face3 Call Trace: [<ffffffff810f20ce>] ? get_empty_filp+0x70/0x12f [<ffffffff810face3>] ? do_filp_open+0x145/0x590 [<ffffffff810ce208>] ? tlb_finish_mmu+0x2a/0x33 [<ffffffff810ce43c>] ? unmap_region+0xd3/0xe2 [<ffffffff810e4393>] ? virt_to_head_page+0x9/0x2d [<ffffffff81103916>] ? alloc_fd+0x69/0x10e [<ffffffff810ef4ed>] ? do_sys_open+0x56/0xfc [<ffffffff81008a02>] ? system_call_fastpath+0x16/0x1b Code: 0f 1f 44 00 00 49 89 c6 fa 66 0f 1f 44 00 00 65 4c 8b 04 25 60 e8 00 00 48 8b 45 00 49 01 c0 49 8b 18 48 85 db 74 0d 48 63 45 18 <48> 8b 04 03 49 89 00 eb 14 4c 89 f9 83 ca ff 44 89 e6 48 89 ef RIP [<ffffffff810e61a3>] kmem_cache_alloc+0x5b/0xe9 This problem is that find_keyring_by_name does not confirm that the keyring is valid before accepting it. Skipping keyrings that have been reduced to a zero count seems the way to go. To this end, use atomic_inc_not_zero() to increment the usage count and skip the candidate keyring if that returns false. The following script _may_ cause the bug to happen, but there's no guarantee as the window of opportunity is small: #!/bin/sh LOOP=100000 USER=dummy_user /bin/su -c "exit;" $USER || { /usr/sbin/adduser -m $USER; add=1; } for ((i=0; i<LOOP; i++)) do /bin/su -c "echo '$i' > /dev/null" $USER done (( add == 1 )) && /usr/sbin/userdel -r $USER exit Note that the nominated user must not be in use. An alternative way of testing this may be: for ((i=0; i<100000; i++)) do keyctl session foo /bin/true || break done >&/dev/null as that uses a keyring named "foo" rather than relying on the user and user-session named keyrings. Reported-by:
Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com> Signed-off-by:
Serge Hallyn <serue@us.ibm.com> Signed-off-by:
James Morris <jmorris@namei.org> Cc: Ben Hutchings <ben@decadent.org.uk> Cc: Chuck Ebbert <cebbert@redhat.com> Signed-off-by:
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Dan Carpenter authored
commit 4d09ec0f upstream. We were using the wrong variable here so the error codes weren't being returned properly. The original code returns -ENOKEY. Signed-off-by:
Dan Carpenter <error27@gmail.com> Signed-off-by:
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Mikulas Patocka authored
commit 102c6ddb upstream. Removed unnecessary 'and' masking: The right shift discards the lower bits so there is no need to clear them. (A later patch needs this change to support a 32-bit chunk_mask.) Signed-off-by:
Mikulas Patocka <mpatocka@redhat.com> Reviewed-by:
Mike Snitzer <snitzer@redhat.com> Reviewed-by:
Jonathan Brassow <jbrassow@redhat.com> Signed-off-by:
Alasdair G Kergon <agk@redhat.com> Signed-off-by:
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Helge Deller authored
commit 550f0d92 upstream. Clear the floating point exception flag before returning to user space. This is needed, else the libc trampoline handler may hit the same SIGFPE again while building up a trampoline to a signal handler. Fixes debian bug #559406. Signed-off-by:
Helge Deller <deller@gmx.de> Signed-off-by:
Kyle McMartin <kyle@mcmartin.ca> Signed-off-by:
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Yin Kangkai authored
commit 765f8361 upstream. jbd-debug and jbd2-debug is currently read-only (S_IRUGO), which is not correct. Make it writable so that we can start debuging. Signed-off-by:
Yin Kangkai <kangkai.yin@intel.com> Reviewed-by:
Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Jan Kara <jack@suse.cz> Cc: Theodore Ts'o <tytso@mit.edu> Signed-off-by:
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Roedel, Joerg authored
This patch fixes a bug in the KVM efer-msr write path. If a guest writes to a reserved efer bit the set_efer function injects the #GP directly. The architecture dependent wrmsr function does not see this, assumes success and advances the rip. This results in a #GP in the guest with the wrong rip. This patch fixes this by reporting efer write errors back to the architectural wrmsr function. Signed-off-by:
Joerg Roedel <joerg.roedel@amd.com> Signed-off-by:
Avi Kivity <avi@redhat.com> Signed-off-by:
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Avi Kivity authored
Signed-off-by:
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Avi Kivity authored
Wallclock writing uses an unprotected global variable to hold the version; this can cause one guest to interfere with another if both write their wallclock at the same time. Acked-by:
Glauber Costa <glommer@redhat.com> Signed-off-by:
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Avi Kivity authored
On svm, kvm_read_pdptr() may require reading guest memory, which can sleep. Push the spinlock into mmu_alloc_roots(), and only take it after we've read the pdptr. Tested-by:
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Shane Wang authored
Per document, for feature control MSR: Bit 1 enables VMXON in SMX operation. If the bit is clear, execution of VMXON in SMX operation causes a general-protection exception. Bit 2 enables VMXON outside SMX operation. If the bit is clear, execution of VMXON outside SMX operation causes a general-protection exception. This patch is to enable this kind of check with SMX for VMXON in KVM. Signed-off-by:Shane Wang <shane.wang@intel.com> Signed-off-by:
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Avi Kivity authored
When cr0.wp=0, we may shadow a gpte having u/s=1 and r/w=0 with an spte having u/s=0 and r/w=1. This allows excessive access if the guest sets cr0.wp=1 and accesses through this spte. Fix by making cr0.wp part of the base role; we'll have different sptes for the two cases and the problem disappears. Signed-off-by:
Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by:
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Sheng Yang authored
kvm_x86_ops->set_efer() would execute vcpu->arch.efer = efer, so the checking of LMA bit didn't work. Signed-off-by:
Sheng Yang <sheng@linux.intel.com> Signed-off-by:
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Avi Kivity authored
The current lmsw implementation allows the guest to clear cr0.pe, contrary to the manual, which breaks EMM386.EXE. Fix by ORing the old cr0.pe with lmsw's operand. Signed-off-by:
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Glauber Costa authored
In recent stress tests, it was found that pvclock-based systems could seriously warp in smp systems. Using ingo's time-warp-test.c, I could trigger a scenario as bad as 1.5mi warps a minute in some systems. (to be fair, it wasn't that bad in most of them). Investigating further, I found out that such warps were caused by the very offset-based calculation pvclock is based on. This happens even on some machines that report constant_tsc in its tsc flags, specially on multi-socket ones. Two reads of the same kernel timestamp at approx the same time, will likely have tsc timestamped in different occasions too. This means the delta we calculate is unpredictable at best, and can probably be smaller in a cpu that is legitimately reading clock in a forward ocasion. Some adjustments on the host could make this window less likely to happen, but still, it pretty much poses as an intrinsic problem of the mechanism. A while ago, I though about using a shared variable anyway, to hold clock last state, but gave up due to the high contention locking was likely to introduce, possibly rendering the thing useless on big machines. I argue, however, that locking is not necessary. We do a read-and-return sequence in pvclock, and between read and return, the global value can have changed. However, it can only have changed by means of an addition of a positive value. So if we detected that our clock timestamp is less than the current global, we know that we need to return a higher one, even though it is not exactly the one we compared to. OTOH, if we detect we're greater than the current time source, we atomically replace the value with our new readings. This do causes contention on big boxes (but big here means *BIG*), but it seems like a good trade off, since it provide us with a time source guaranteed to be stable wrt time warps. After this patch is applied, I don't see a single warp in time during 5 days of execution, in any of the machines I saw them before. Signed-off-by:
Zachary Amsden <zamsden@redhat.com> CC: Jeremy Fitzhardinge <jeremy@goop.org> CC: Avi Kivity <avi@redhat.com> CC: Marcelo Tosatti <mtosatti@redhat.com> CC: Zachary Amsden <zamsden@redhat.com> Signed-off-by:
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Wei Yongjun authored
If fail to create the vcpu, we should not create the debugfs for it. Signed-off-by:
Alexander Graf <agraf@suse.de> Cc: stable@kernel.org Signed-off-by:
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