| Message ID | 38cc241c40a8ef2775e304d366bcd07df733ecf0.1d66512d.85e4.41a5.8cf7.4c1fdb05d775@feishu.cn (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | riscv: KVM: Remove unnecessary vcpu kick | expand |
On Tue, Feb 18, 2025 at 04:00:24PM +0800, 项文成 wrote: > From 30dd00f6886119ecc5c39b6b88f8617a57e598fc Mon Sep 17 00:00:00 2001 > From: BillXiang <xiangwencheng@lanxincomputing.com> > Date: Tue, 18 Feb 2025 15:45:52 +0800 > Subject: [PATCH] riscv: KVM: Remove unnecessary vcpu kick > > Hello everyone, > 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. The above should be in a cover letter so the commit message can be written following the guidelines of [1] [1] Documentation/process/submitting-patches.rst > > 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); We can't completely remove the kick, but we could replace it with a kvm_vcpu_wake_up(). There's also a kick in kvm_riscv_vcpu_vstimer_expired() which could be a kvm_vcpu_wake_up() when hideleg has IRQ_VS_TIMER set (which it currently always does). Thanks, drew > } else { > eix = &imsic->swfile->eix[iid / BITS_PER_TYPE(u64)]; > set_bit(iid & (BITS_PER_TYPE(u64) - 1), eix->eip); > -- > 2.46.2 > > -- > kvm-riscv mailing list > kvm-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kvm-riscv
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);