Patch "Revert KVM: MIPS: Drop other CPU ASIDs on guest MMU changes" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

Revert KVM: MIPS: Drop other CPU ASIDs on guest MMU changes

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
revert-kvm-mips-drop-other-cpu-asids-on-guest-mmu-changes.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Date: Sun, 13 Nov 2016 12:16:15 +0100
To: Greg KH <[email protected]>
From: Greg Kroah-Hartman <[email protected]>
Subject: Revert KVM: MIPS: Drop other CPU ASIDs on guest MMU changes

This reverts commit d450527ad04ad180636679aeb3161ec58079f1ba which was commit 91e4f1b6073dd680d86cdb7e42d7cccca9db39d8 upstream as it was incorrect. A fixed version will be forthcoming.

---
 arch/mips/kvm/emulate.c |   63 +++++++-----------------------------------------
 1 file changed, 10 insertions(+), 53 deletions(-)

@@ -807,47 +807,6 @@ enum emulation_result kvm_mips_emul_tlbr
 	return EMULATE_FAIL;
 }
 
-/**
- * kvm_mips_invalidate_guest_tlb() - Indicates a change in guest MMU map.
- * @vcpu:	VCPU with changed mappings.
- * @tlb:	TLB entry being removed.
- *
- * This is called to indicate a single change in guest MMU mappings, so that we
- * can arrange TLB flushes on this and other CPUs.
- */
-static void kvm_mips_invalidate_guest_tlb(struct kvm_vcpu *vcpu,
-					  struct kvm_mips_tlb *tlb)
-{
-	int cpu, i;
-	bool user;
-
-	/* No need to flush for entries which are already invalid */
-	if (!((tlb->tlb_lo[0] | tlb->tlb_lo[1]) & ENTRYLO_V))
-		return;
-	/* User address space doesn't need flushing for KSeg2/3 changes */
-	user = tlb->tlb_hi < KVM_GUEST_KSEG0;
-
-	preempt_disable();
-
-	/*
-	 * Probe the shadow host TLB for the entry being overwritten, if one
-	 * matches, invalidate it
-	 */
-	kvm_mips_host_tlb_inv(vcpu, tlb->tlb_hi);
-
-	/* Invalidate the whole ASID on other CPUs */
-	cpu = smp_processor_id();
-	for_each_possible_cpu(i) {
-		if (i == cpu)
-			continue;
-		if (user)
-			vcpu->arch.guest_user_asid[i] = 0;
-		vcpu->arch.guest_kernel_asid[i] = 0;
-	}
-
-	preempt_enable();
-}
-
 /* Write Guest TLB Entry @ Index */
 enum emulation_result kvm_mips_emul_tlbwi(struct kvm_vcpu *vcpu)
 {

@@ -867,8 +826,11 @@ enum emulation_result kvm_mips_emul_tlbw
 	}
 
 	tlb = &vcpu->arch.guest_tlb[index];
-
-	kvm_mips_invalidate_guest_tlb(vcpu, tlb);
+	/*
+	 * Probe the shadow host TLB for the entry being overwritten, if one
+	 * matches, invalidate it
+	 */
+	kvm_mips_host_tlb_inv(vcpu, tlb->tlb_hi);
 
 	tlb->tlb_mask = kvm_read_c0_guest_pagemask(cop0);
 	tlb->tlb_hi = kvm_read_c0_guest_entryhi(cop0);

@@ -897,7 +859,11 @@ enum emulation_result kvm_mips_emul_tlbw
 
 	tlb = &vcpu->arch.guest_tlb[index];
 
-	kvm_mips_invalidate_guest_tlb(vcpu, tlb);
+	/*
+	 * Probe the shadow host TLB for the entry being overwritten, if one
+	 * matches, invalidate it
+	 */
+	kvm_mips_host_tlb_inv(vcpu, tlb->tlb_hi);
 
 	tlb->tlb_mask = kvm_read_c0_guest_pagemask(cop0);
 	tlb->tlb_hi = kvm_read_c0_guest_entryhi(cop0);

@@ -1016,7 +982,6 @@ enum emulation_result kvm_mips_emulate_C
 	int32_t rt, rd, copz, sel, co_bit, op;
 	uint32_t pc = vcpu->arch.pc;
 	unsigned long curr_pc;
-	int cpu, i;
 
 	/*
 	 * Update PC and hold onto current PC in case there is

@@ -1124,16 +1089,8 @@ enum emulation_result kvm_mips_emulate_C
 						vcpu->arch.gprs[rt]
 						& ASID_MASK);
 
-					preempt_disable();
 					/* Blow away the shadow host TLBs */
 					kvm_mips_flush_host_tlb(1);
-					cpu = smp_processor_id();
-					for_each_possible_cpu(i)
-						if (i != cpu) {
-							vcpu->arch.guest_user_asid[i] = 0;
-							vcpu->arch.guest_kernel_asid[i] = 0;
-						}
-					preempt_enable();
 				}
 				kvm_write_c0_guest_entryhi(cop0,
 							   vcpu->arch.gprs[rt]);

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/drm-amdgpu-fix-dp-mode-validation.patch queue-4.4/ipmr-ip6mr-fix-scheduling-while-atomic-and-a-deadlock-with-ipmr_get_route.patch queue-4.4/of-silence-warnings-due-to-max-usage.patch queue-4.4/ip6_gre-fix-flowi6_proto-value-in-ip6gre_xmit_other.patch queue-4.4/drm-radeon-fix-dp-mode-validation.patch queue-4.4/rtnetlink-add-rtnexthop-offload-flag-to-compare-mask.patch queue-4.4/net-sctp-forbid-negative-length.patch queue-4.4/ip6_tunnel-fix-ip6_tnl_lookup.patch queue-4.4/net-sched-act_vlan-push-skb-data-to-mac_header-prior-calling-skb_vlan_-functions.patch queue-4.4/packet-call-fanout_release-while-unregistering-a-netdev.patch queue-4.4/tg3-avoid-null-pointer-dereference-in-tg3_io_error_detected.patch queue-4.4/kvm-mips-drop-other-cpu-asids-on-guest-mmu-changes.patch queue-4.4/net-add-recursion-limit-to-gro.patch queue-4.4/bridge-multicast-restore-perm-router-ports-on-multicast-enable.patch queue-4.4/tcp-fix-wrong-checksum-calculation-on-mtu-probing.patch queue-4.4/revert-kvm-mips-drop-other-cpu-asids-on-guest-mmu-changes.patch queue-4.4/net-sched-filters-fix-notification-of-filter-delete-with-proper-handle.patch queue-4.4/ipv4-use-the-right-lock-for-ping_group_range.patch queue-4.4/ipv4-disable-bh-in-set_ping_group_range.patch queue-4.4/drm-amdgpu-dp-add-back-special-handling-for-nutmeg.patch queue-4.4/tcp-fix-a-compile-error-in-dbgundo.patch queue-4.4/net-avoid-sk_forward_alloc-overflows.patch queue-4.4/udp-fix-ip_checksum-handling.patch queue-4.4/net-add-netdev-all_adj_list-refcnt-propagation-to-fix-panic.patch queue-4.4/netlink-do-not-enter-direct-reclaim-from-netlink_dump.patch queue-4.4/net-fec-set-mac-address-unconditionally.patch queue-4.4/ipv6-tcp-restore-ip6cb-for-pktoptions-skbs.patch queue-4.4/tcp-fix-overflow-in-__tcp_retransmit_skb.patch queue-4.4/ipv6-correctly-add-local-routes-when-lo-goes-up.patch queue-4.4/packet-on-direct_xmit-limit-tso-and-csum-to-supported-devices.patch queue-4.4/sctp-validate-chunk-len-before-actually-using-it.patch queue-4.4/net-pktgen-remove-rcu-locking-in-pktgen_change_name.patch queue-4.4/drm-radeon-dp-add-back-special-handling-for-nutmeg.patch queue-4.4/net-pktgen-fix-pkt_size.patch