linux-kernel - [PATCH 3/7] KVM: x86: Check vCPUs before enqueuing TLB flushes in kvm_hv_flush

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Message-ID: <20241004140810.34231-4-nikwip@amazon.de>
Date: Fri, 4 Oct 2024 14:08:06 +0000
From: Nikolas Wipper <nikwip@...zon.de>
To: Vitaly Kuznetsov <vkuznets@...hat.com>
CC: Nicolas Saenz Julienne <nsaenz@...zon.com>, Alexander Graf
	<graf@...zon.de>, James Gowans <jgowans@...zon.com>,
	<nh-open-source@...zon.com>, Sean Christopherson <seanjc@...gle.com>, "Paolo
 Bonzini" <pbonzini@...hat.com>, Thomas Gleixner <tglx@...utronix.de>, "Ingo
 Molnar" <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Dave Hansen
	<dave.hansen@...ux.intel.com>, Nikolas Wipper <nik.wipper@....de>,
	<linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>, <x86@...nel.org>,
	<linux-doc@...r.kernel.org>, <linux-kselftest@...r.kernel.org>, "Nikolas
 Wipper" <nikwip@...zon.de>
Subject: [PATCH 3/7] KVM: x86: Check vCPUs before enqueuing TLB flushes in kvm_hv_flush_tlb()

In Hyper-V's kvm_hv_flush_tlb(), check targeted vCPUs and store them in a
bitmap before flushing their TLBs. In a subsequent commit, remote TLB
flushes may need to be aborted, so allow checking for that before starting
to enque the flushes.

No functional change intended.

Signed-off-by: Nikolas Wipper <nikwip@...zon.de>
---
 arch/x86/kvm/hyperv.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 6e7941ed25ae..e68fbc0c7fc1 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -2134,26 +2134,21 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
 	 * analyze it here, flush TLB regardless of the specified address space.
 	 */
 	if (all_cpus && !is_guest_mode(vcpu)) {
+		bitmap_zero(vcpu_mask, KVM_MAX_VCPUS);
+
 		kvm_for_each_vcpu(i, v, kvm) {
-			tlb_flush_fifo = kvm_hv_get_tlb_flush_fifo(v, false);
-			hv_tlb_flush_enqueue(v, tlb_flush_fifo,
-					     tlb_flush_entries, hc->rep_cnt);
+			__set_bit(i, vcpu_mask);
 		}
-
-		kvm_make_all_cpus_request(kvm, KVM_REQ_HV_TLB_FLUSH);
 	} else if (!is_guest_mode(vcpu)) {
 		sparse_set_to_vcpu_mask(kvm, sparse_banks, valid_bank_mask, vcpu_mask);
 
 		for_each_set_bit(i, vcpu_mask, KVM_MAX_VCPUS) {
 			v = kvm_get_vcpu(kvm, i);
-			if (!v)
+			if (!v) {
+				__clear_bit(i, vcpu_mask);
 				continue;
-			tlb_flush_fifo = kvm_hv_get_tlb_flush_fifo(v, false);
-			hv_tlb_flush_enqueue(v, tlb_flush_fifo,
-					     tlb_flush_entries, hc->rep_cnt);
+			}
 		}
-
-		kvm_make_vcpus_request_mask(kvm, KVM_REQ_HV_TLB_FLUSH, vcpu_mask);
 	} else {
 		struct kvm_vcpu_hv *hv_v;
 
@@ -2181,14 +2176,19 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
 				continue;
 
 			__set_bit(i, vcpu_mask);
-			tlb_flush_fifo = kvm_hv_get_tlb_flush_fifo(v, true);
-			hv_tlb_flush_enqueue(v, tlb_flush_fifo,
-					     tlb_flush_entries, hc->rep_cnt);
 		}
+	}
 
-		kvm_make_vcpus_request_mask(kvm, KVM_REQ_HV_TLB_FLUSH, vcpu_mask);
+	for_each_set_bit(i, vcpu_mask, KVM_MAX_VCPUS) {
+		v = kvm_get_vcpu(kvm, i);
+
+		tlb_flush_fifo = kvm_hv_get_tlb_flush_fifo(v, is_guest_mode(vcpu));
+		hv_tlb_flush_enqueue(v, tlb_flush_fifo,
+				     tlb_flush_entries, hc->rep_cnt);
 	}
 
+	kvm_make_vcpus_request_mask(kvm, KVM_REQ_HV_TLB_FLUSH, vcpu_mask);
+
 ret_success:
 	/* We always do full TLB flush, set 'Reps completed' = 'Rep Count' */
 	return (u64)HV_STATUS_SUCCESS |
-- 
2.40.1




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