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From: Jiri Slaby <jslaby@suse.cz>
To: stable@vger.kernel.org
Cc: lguest@lists.ozlabs.org,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Rusty Russell <rusty@rustcorp.com.au>,
	Xen-devel <xen-devel@lists.xen.org>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Jiri Slaby <jslaby@suse.cz>, Thomas Gleixner <tglx@linutronix.de>
Subject: [patch added to the 3.12 stable tree] x86/cpu: Fix SMAP check in PVOPS environments
Date: Tue,  5 Jan 2016 16:28:29 +0100	[thread overview]
Message-ID: <1452007726-3747-28-git-send-email-jslaby__11686.4464748234$1452007902$gmane$org@suse.cz> (raw)
In-Reply-To: <1452007726-3747-1-git-send-email-jslaby@suse.cz>

From: Andrew Cooper <andrew.cooper3@citrix.com>

This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.

===============

commit 581b7f158fe0383b492acd1ce3fb4e99d4e57808 upstream.

There appears to be no formal statement of what pv_irq_ops.save_fl() is
supposed to return precisely.  Native returns the full flags, while lguest and
Xen only return the Interrupt Flag, and both have comments by the
implementations stating that only the Interrupt Flag is looked at.  This may
have been true when initially implemented, but no longer is.

To make matters worse, the Xen PVOP leaves the upper bits undefined, making
the BUG_ON() undefined behaviour.  Experimentally, this now trips for 32bit PV
guests on Broadwell hardware.  The BUG_ON() is consistent for an individual
build, but not consistent for all builds.  It has also been a sitting timebomb
since SMAP support was introduced.

Use native_save_fl() instead, which will obtain an accurate view of the AC
flag.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Tested-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: <lguest@lists.ozlabs.org>
Cc: Xen-devel <xen-devel@lists.xen.org>
Link: http://lkml.kernel.org/r/1433323874-6927-1-git-send-email-andrew.cooper3@citrix.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 arch/x86/kernel/cpu/common.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 6db4828574ef..9364936b47c2 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -280,10 +280,9 @@ __setup("nosmap", setup_disable_smap);
 
 static __always_inline void setup_smap(struct cpuinfo_x86 *c)
 {
-	unsigned long eflags;
+	unsigned long eflags = native_save_fl();
 
 	/* This should have been cleared long ago */
-	raw_local_save_flags(eflags);
 	BUG_ON(eflags & X86_EFLAGS_AC);
 
 	if (cpu_has(c, X86_FEATURE_SMAP)) {
-- 
2.6.4

  parent reply	other threads:[~2016-01-05 15:28 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-05 15:28 [patch added to the 3.12 stable tree] ipv6: fix tunnel error handling Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] MIPS: KVM: Fix ASID restoration logic Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] MIPS: KVM: Fix CACHE immediate offset sign extension Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] MIPS: KVM: Uninit VCPU in vcpu_create error path Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] unix: avoid use-after-free in ep_remove_wait_queue Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] packet: do skb_probe_transport_header when we actually have data Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] packet: infer protocol from ethernet header if unset Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] sctp: translate host order to network order when setting a hmacid Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] snmp: Remove duplicate OUTMCAST stat increment Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] net: qmi_wwan: add XS Stick W100-2 from 4G Systems Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] tcp: md5: fix lockdep annotation Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] tcp: initialize tp->copied_seq in case of cross SYN connection Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] net, scm: fix PaX detected msg_controllen overflow in scm_detach_fds Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] net: ipmr: fix static mfc/dev leaks on table destruction Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] net: ip6mr: " Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] broadcom: fix PHY_ID_BCM5481 entry in the id table Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] ipv6: distinguish frag queues by device for multicast and link-local packets Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] ipv6: add complete rcu protection around np->opt Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] net/neighbour: fix crash at dumping device-agnostic proxy entries Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] ipv6: sctp: implement sctp_v6_destroy_sock() Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] Bluetooth: ath3k: Add support of 04ca:300d AR3012 device Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] ARM: 8426/1: dma-mapping: add missing range check in dma_mmap() Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] ARM: 8427/1: dma-mapping: add support for offset parameter " Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] ARM: common: edma: Fix channel parameter for irq callbacks Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] x86/setup: Extend low identity map to cover whole kernel range Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] x86/setup: Fix low identity map for >= 2GB " Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] x86/cpu: Call verify_cpu() after having entered long mode too Jiri Slaby
2016-01-05 15:28 ` Jiri Slaby [this message]
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] x86/cpu: Fix SMAP check in PVOPS environments Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] mac80211: fix driver RSSI event calculations Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] net: mvneta: Fix CPU_MAP registers initialisation Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] mwifiex: fix mwifiex_rdeeprom_read() Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] staging: rtl8712: Add device ID for Sitecom WLA2100 Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] Bluetooth: hidp: fix device disconnect on idle timeout Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] Bluetooth: ath3k: Add new AR3012 0930:021c id Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] Bluetooth: ath3k: Add support of AR3012 0cf3:817b device Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] can: sja1000: clear interrupts on start Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] arm64: Fix compat register mappings Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] usblp: do not set TASK_INTERRUPTIBLE before lock Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] usb: musb: core: fix order of arguments to ulpi write callback Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] USB: ti_usb_3410_5052: Add Honeywell HGI80 ID Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] USB: serial: option: add support for Novatel MiFi USB620L Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] USB: option: add XS Stick W100-2 from 4G Systems Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] ALSA: usb-audio: add packet size quirk for the Medeli DD305 Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] ALSA: usb-audio: prevent CH345 multiport output SysEx corruption Jiri Slaby
2016-01-05 15:28 ` [patch added to the 3.12 stable tree] ALSA: usb-audio: work around CH345 input " Jiri Slaby

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