From: Sean Christopherson <seanjc@google.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Jacob Pan <jacob.jun.pan@linux.intel.com>,
Jim Mattson <jmattson@google.com>
Subject: [PATCH 7/8] KVM: VMX: Use arch_xchg() when processing PIR to avoid instrumentation
Date: Fri, 14 Mar 2025 20:06:28 -0700 [thread overview]
Message-ID: <20250315030630.2371712-8-seanjc@google.com> (raw)
In-Reply-To: <20250315030630.2371712-1-seanjc@google.com>
Use arch_xchg() when moving IRQs from the PIR to the vIRR, purely to avoid
instrumentation so that KVM is compatible with the needs of posted MSI.
This will allow extracting the core PIR logic to common code and sharing
it between KVM and posted MSI handling.
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/lapic.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index d7e36faffc72..b65e0f7223fe 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -680,7 +680,7 @@ bool __kvm_apic_update_irr(unsigned long *pir, void *regs, int *max_irr)
if (!pir_vals[i])
continue;
- pir_vals[i] = xchg(&pir[i], 0);
+ pir_vals[i] = arch_xchg(&pir[i], 0);
}
for (i = vec = 0; i <= 7; i++, vec += 32) {
--
2.49.0.rc1.451.g8f38331e32-goog
next prev parent reply other threads:[~2025-03-15 3:06 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-15 3:06 [PATCH 0/8] x86/irq: KVM: Optimize KVM's PIR harvesting Sean Christopherson
2025-03-15 3:06 ` [PATCH 1/8] x86/irq: Ensure initial PIR loads are performed exactly once Sean Christopherson
2025-03-17 11:23 ` Thomas Gleixner
2025-03-15 3:06 ` [PATCH 2/8] x86/irq: Track if IRQ was found in PIR during initial loop (to load PIR vals) Sean Christopherson
2025-03-17 13:13 ` Thomas Gleixner
2025-03-17 16:53 ` Sean Christopherson
2025-03-18 9:27 ` Thomas Gleixner
2025-03-15 3:06 ` [PATCH 3/8] KVM: VMX: Ensure vIRR isn't reloaded at odd times when sync'ing PIR Sean Christopherson
2025-03-15 3:06 ` [PATCH 4/8] x86/irq: KVM: Track PIR bitmap as an "unsigned long" array Sean Christopherson
2025-03-15 3:06 ` [PATCH 5/8] KVM: VMX: Process PIR using 64-bit accesses on 64-bit kernels Sean Christopherson
2025-03-15 3:06 ` [PATCH 6/8] KVM: VMX: Isolate pure loads from atomic XCHG when processing PIR Sean Christopherson
2025-03-15 3:06 ` Sean Christopherson [this message]
2025-03-15 3:06 ` [PATCH 8/8] x86/irq: KVM: Add helper for harvesting PIR to deduplicate KVM and posted MSIs Sean Christopherson
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