From: Andrew Jones <ajones@ventanamicro.com>
To: BillXiang <xiangwencheng@lanxincomputing.com>
Cc: anup@brainfault.org, 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: Re: [PATCH] riscv: KVM: Remove unnecessary vcpu kick
Date: Wed, 19 Feb 2025 09:36:05 +0100 [thread overview]
Message-ID: <20250219-badec60b9b12834cf534dcbf@orel> (raw)
In-Reply-To: <20250219015426.1939-1-xiangwencheng@lanxincomputing.com>
On Wed, Feb 19, 2025 at 09:54:26AM +0800, BillXiang wrote:
> Thank you Andrew Jones, forgive my errors in the last email.
From here down is all exactly the same as your first email, which I
already completely replied to.
> 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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next prev parent reply other threads:[~2025-02-19 8:52 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-19 1:54 [PATCH] riscv: KVM: Remove unnecessary vcpu kick BillXiang
2025-02-19 8:36 ` Andrew Jones [this message]
2025-02-19 8:51 ` Radim Krčmář
2025-02-20 7:12 ` xiangwencheng
2025-02-20 8:01 ` Andrew Jones
2025-02-20 8:17 ` xiangwencheng
2025-02-20 8:50 ` Radim Krčmář
2025-02-20 12:14 ` Andrew Jones
-- strict thread matches above, loose matches on Subject: below --
2025-02-18 8:00 项文成
2025-02-18 17:48 ` Andrew Jones
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