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From: Nadav Amit <namit@vmware.com>
To: Peter Zijlstra <peterz@infradead.org>, Andy Lutomirski <luto@kernel.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Nadav Amit <namit@vmware.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	kvm@vger.kernel.org
Subject: [PATCH 6/9] KVM: x86: Provide paravirtualized flush_tlb_multi()
Date: Wed, 12 Jun 2019 23:48:10 -0700
Message-ID: <20190613064813.8102-7-namit@vmware.com> (raw)
In-Reply-To: <20190613064813.8102-1-namit@vmware.com>

Support the new interface of flush_tlb_multi, which also flushes the
local CPU's TLB, instead of flush_tlb_others that does not. This
interface is more performant since it parallelize remote and local TLB
flushes.

The actual implementation of flush_tlb_multi() is almost identical to
that of flush_tlb_others().

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org
Signed-off-by: Nadav Amit <namit@vmware.com>
---
 arch/x86/kernel/kvm.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 00d81e898717..d00d551d4a2a 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -580,7 +580,7 @@ static void __init kvm_apf_trap_init(void)
 
 static DEFINE_PER_CPU(cpumask_var_t, __pv_tlb_mask);
 
-static void kvm_flush_tlb_others(const struct cpumask *cpumask,
+static void kvm_flush_tlb_multi(const struct cpumask *cpumask,
 			const struct flush_tlb_info *info)
 {
 	u8 state;
@@ -594,6 +594,11 @@ static void kvm_flush_tlb_others(const struct cpumask *cpumask,
 	 * queue flush_on_enter for pre-empted vCPUs
 	 */
 	for_each_cpu(cpu, flushmask) {
+		/*
+		 * The local vCPU is never preempted, so we do not explicitly
+		 * skip check for local vCPU - it will never be cleared from
+		 * flushmask.
+		 */
 		src = &per_cpu(steal_time, cpu);
 		state = READ_ONCE(src->preempted);
 		if ((state & KVM_VCPU_PREEMPTED)) {
@@ -603,7 +608,7 @@ static void kvm_flush_tlb_others(const struct cpumask *cpumask,
 		}
 	}
 
-	native_flush_tlb_others(flushmask, info);
+	native_flush_tlb_multi(flushmask, info);
 }
 
 static void __init kvm_guest_init(void)
@@ -628,9 +633,8 @@ static void __init kvm_guest_init(void)
 	if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
 	    !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
 	    kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
-		pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;
+		pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi;
 		pv_ops.mmu.tlb_remove_table = tlb_remove_table;
-		static_key_disable(&flush_tlb_multi_enabled.key);
 	}
 
 	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
-- 
2.20.1


  parent reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190613064813.8102-1-namit@vmware.com>
2019-06-13  6:48 ` [PATCH 4/9] x86/mm/tlb: Flush remote and local TLBs concurrently Nadav Amit
2019-06-25 21:29   ` Dave Hansen
2019-06-26  2:35     ` Nadav Amit
2019-06-26  3:00       ` Dave Hansen
2019-06-26  3:32         ` Nadav Amit
2019-06-26  3:36   ` Andy Lutomirski
2019-06-26  3:48     ` Nadav Amit
2019-06-26  3:51       ` Andy Lutomirski
2019-06-13  6:48 ` Nadav Amit [this message]
2019-06-25 21:40   ` [PATCH 6/9] KVM: x86: Provide paravirtualized flush_tlb_multi() Dave Hansen
2019-06-26  2:39     ` Nadav Amit
2019-06-26  3:35       ` Andy Lutomirski
2019-06-26  3:41         ` Nadav Amit
2019-06-26  3:56           ` Andy Lutomirski
2019-06-26  6:30             ` Nadav Amit
2019-06-26 16:37               ` Andy Lutomirski
2019-06-26 17:41                 ` Vitaly Kuznetsov
2019-06-26 18:21                   ` Andy Lutomirski

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