Merge 4.4.154 into android-4.4-p

Changes in 4.4.154
	sched/sysctl: Check user input value of sysctl_sched_time_avg
	Cipso: cipso_v4_optptr enter infinite loop
	vti6: fix PMTU caching and reporting on xmit
	xfrm: fix missing dst_release() after policy blocking lbcast and multicast
	xfrm: free skb if nlsk pointer is NULL
	mac80211: add stations tied to AP_VLANs during hw reconfig
	nl80211: Add a missing break in parse_station_flags
	drm/bridge: adv7511: Reset registers on hotplug
	scsi: libiscsi: fix possible NULL pointer dereference in case of TMF
	drm/imx: imx-ldb: disable LDB on driver bind
	drm/imx: imx-ldb: check if channel is enabled before printing warning
	usb: gadget: r8a66597: Fix two possible sleep-in-atomic-context bugs in init_controller()
	usb: gadget: r8a66597: Fix a possible sleep-in-atomic-context bugs in r8a66597_queue()
	usb/phy: fix PPC64 build errors in phy-fsl-usb.c
	tools: usb: ffs-test: Fix build on big endian systems
	usb: gadget: f_uac2: fix endianness of 'struct cntrl_*_lay3'
	tools/power turbostat: fix -S on UP systems
	net: caif: Add a missing rcu_read_unlock() in caif_flow_cb
	qed: Fix possible race for the link state value.
	atl1c: reserve min skb headroom
	net: prevent ISA drivers from building on PPC32
	can: mpc5xxx_can: check of_iomap return before use
	i2c: davinci: Avoid zero value of CLKH
	media: staging: omap4iss: Include asm/cacheflush.h after generic includes
	bnx2x: Fix invalid memory access in rss hash config path.
	net: axienet: Fix double deregister of mdio
	fscache: Allow cancelled operations to be enqueued
	cachefiles: Fix refcounting bug in backing-file read monitoring
	cachefiles: Wait rather than BUG'ing on "Unexpected object collision"
	selftests/ftrace: Add snapshot and tracing_on test case
	zswap: re-check zswap_is_full() after do zswap_shrink()
	tools/power turbostat: Read extended processor family from CPUID
	Revert "MIPS: BCM47XX: Enable 74K Core ExternalSync for PCIe erratum"
	enic: handle mtu change for vf properly
	arc: fix build errors in arc/include/asm/delay.h
	arc: fix type warnings in arc/mm/cache.c
	drivers: net: lmc: fix case value for target abort error
	scsi: fcoe: drop frames in ELS LOGO error path
	scsi: vmw_pvscsi: Return DID_RESET for status SAM_STAT_COMMAND_TERMINATED
	mm/memory.c: check return value of ioremap_prot
	cifs: add missing debug entries for kconfig options
	cifs: check kmalloc before use
	smb3: Do not send SMB3 SET_INFO if nothing changed
	smb3: don't request leases in symlink creation and query
	btrfs: don't leak ret from do_chunk_alloc
	s390/kvm: fix deadlock when killed by oom
	ext4: check for NUL characters in extended attribute's name
	ext4: sysfs: print ext4_super_block fields as little-endian
	ext4: reset error code in ext4_find_entry in fallback
	arm64: mm: check for upper PAGE_SHIFT bits in pfn_valid()
	KVM: arm/arm64: Skip updating PTE entry if no change
	KVM: arm/arm64: Skip updating PMD entry if no change
	x86/speculation/l1tf: Fix overflow in l1tf_pfn_limit() on 32bit
	x86/speculation/l1tf: Fix off-by-one error when warning that system has too much RAM
	x86/speculation/l1tf: Suggest what to do on systems with too much RAM
	x86/process: Re-export start_thread()
	fuse: Don't access pipe->buffers without pipe_lock()
	fuse: fix double request_end()
	fuse: fix unlocked access to processing queue
	fuse: umount should wait for all requests
	fuse: Fix oops at process_init_reply()
	fuse: Add missed unlock_page() to fuse_readpages_fill()
	udl-kms: change down_interruptible to down
	udl-kms: handle allocation failure
	udl-kms: fix crash due to uninitialized memory
	ASoC: dpcm: don't merge format from invalid codec dai
	ASoC: sirf: Fix potential NULL pointer dereference
	pinctrl: freescale: off by one in imx1_pinconf_group_dbg_show()
	x86/irqflags: Mark native_restore_fl extern inline
	x86/spectre: Add missing family 6 check to microcode check
	s390: fix br_r1_trampoline for machines without exrl
	s390/qdio: reset old sbal_state flags
	s390/pci: fix out of bounds access during irq setup
	kprobes: Make list and blacklist root user read only
	MIPS: Correct the 64-bit DSP accumulator register size
	MIPS: lib: Provide MIPS64r6 __multi3() for GCC < 7
	scsi: sysfs: Introduce sysfs_{un,}break_active_protection()
	scsi: core: Avoid that SCSI device removal through sysfs triggers a deadlock
	iscsi target: fix session creation failure handling
	cdrom: Fix info leak/OOB read in cdrom_ioctl_drive_status
	Linux 4.4.154

Change-Id: I1d173ebf72efb115b4889880cc2989b0ca7d751e
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

1 files changed, 31 insertions, 11 deletions

diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index e8835d4e173c..e0267532bd4e 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -892,19 +892,35 @@ static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache
 	pmd = stage2_get_pmd(kvm, cache, addr);
 	VM_BUG_ON(!pmd);
 
-	/*
-	 * Mapping in huge pages should only happen through a fault.  If a
-	 * page is merged into a transparent huge page, the individual
-	 * subpages of that huge page should be unmapped through MMU
-	 * notifiers before we get here.
-	 *
-	 * Merging of CompoundPages is not supported; they should become
-	 * splitting first, unmapped, merged, and mapped back in on-demand.
-	 */
-	VM_BUG_ON(pmd_present(*pmd) && pmd_pfn(*pmd) != pmd_pfn(*new_pmd));
-
 	old_pmd = *pmd;
 	if (pmd_present(old_pmd)) {
+		/*
+		 * Multiple vcpus faulting on the same PMD entry, can
+		 * lead to them sequentially updating the PMD with the
+		 * same value. Following the break-before-make
+		 * (pmd_clear() followed by tlb_flush()) process can
+		 * hinder forward progress due to refaults generated
+		 * on missing translations.
+		 *
+		 * Skip updating the page table if the entry is
+		 * unchanged.
+		 */
+		if (pmd_val(old_pmd) == pmd_val(*new_pmd))
+			return 0;
+
+		/*
+		 * Mapping in huge pages should only happen through a
+		 * fault.  If a page is merged into a transparent huge
+		 * page, the individual subpages of that huge page
+		 * should be unmapped through MMU notifiers before we
+		 * get here.
+		 *
+		 * Merging of CompoundPages is not supported; they
+		 * should become splitting first, unmapped, merged,
+		 * and mapped back in on-demand.
+		 */
+		VM_BUG_ON(pmd_pfn(old_pmd) != pmd_pfn(*new_pmd));
+
 		pmd_clear(pmd);
 		kvm_tlb_flush_vmid_ipa(kvm, addr);
 	} else {
@@ -961,6 +977,10 @@ static int stage2_set_pte(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
 	/* Create 2nd stage page table mapping - Level 3 */
 	old_pte = *pte;
 	if (pte_present(old_pte)) {
+		/* Skip page table update if there is no change */
+		if (pte_val(old_pte) == pte_val(*new_pte))
+			return 0;
+
 		kvm_set_pte(pte, __pte(0));
 		kvm_tlb_flush_vmid_ipa(kvm, addr);
 	} else {