[PATCH] riscv: KVM: Remove unnecessary vcpu kick

From: "BillXiang" <xiangwencheng@lanxincomputing.com>
To: <anup@brainfault.org>
Cc: <ajones@ventanamicro.com>, <xiangwencheng@lanxincomputing.com>,
	 <kvm-riscv@lists.infradead.org>, <kvm@vger.kernel.org>,
	 <linux-riscv@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>,  <atishp@atishpatra.org>,
	<paul.walmsley@sifive.com>,  <palmer@dabbelt.com>,
	<aou@eecs.berkeley.edu>
Subject: [PATCH] riscv: KVM: Remove unnecessary vcpu kick
Date: Wed, 19 Feb 2025 09:54:26 +0800	[thread overview]
Message-ID: <20250219015426.1939-1-xiangwencheng@lanxincomputing.com> (raw)

Thank you Andrew Jones, forgive my errors in the last email.
I'm wondering whether it's necessary to kick the virtual hart
after writing to the vsfile of IMSIC.
From my understanding, writing to the vsfile should directly
forward the interrupt as MSI to the virtual hart. This means that
an additional kick should not be necessary, as it would cause the
vCPU to exit unnecessarily and potentially degrade performance.
I've tested this behavior in QEMU, and it seems to work perfectly
fine without the extra kick.
Would appreciate any insights or confirmation on this!
Best regards.

Signed-off-by: BillXiang <xiangwencheng@lanxincomputing.com>
---
 arch/riscv/kvm/aia_imsic.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/riscv/kvm/aia_imsic.c b/arch/riscv/kvm/aia_imsic.c
index a8085cd8215e..29ef9c2133a9 100644
--- a/arch/riscv/kvm/aia_imsic.c
+++ b/arch/riscv/kvm/aia_imsic.c
@@ -974,7 +974,6 @@ int kvm_riscv_vcpu_aia_imsic_inject(struct kvm_vcpu *vcpu,
 
 	if (imsic->vsfile_cpu >= 0) {
 		writel(iid, imsic->vsfile_va + IMSIC_MMIO_SETIPNUM_LE);
-		kvm_vcpu_kick(vcpu);
 	} else {
 		eix = &imsic->swfile->eix[iid / BITS_PER_TYPE(u64)];
 		set_bit(iid & (BITS_PER_TYPE(u64) - 1), eix->eip);
-- 
2.46.2

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