From: Paolo Bonzini <pbonzini@redhat.com> To: Anup Patel <Anup.Patel@wdc.com>, Palmer Dabbelt <palmer@sifive.com>, Paul Walmsley <paul.walmsley@sifive.com>, Radim K <rkrcmar@redhat.com> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>, Thomas Gleixner <tglx@linutronix.de>, Atish Patra <Atish.Patra@wdc.com>, Alistair Francis <Alistair.Francis@wdc.com>, Damien Le Moal <Damien.LeMoal@wdc.com>, Christoph Hellwig <hch@infradead.org>, Anup Patel <anup@brainfault.org>, "kvm@vger.kernel.org" <kvm@vger.kernel.org>, "linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org> Subject: Re: [RFC PATCH 13/16] RISC-V: KVM: Add timer functionality Date: Tue, 30 Jul 2019 13:26:38 +0200 [thread overview] Message-ID: <abedb067-b91f-8821-9bce-d27f6c4efdee@redhat.com> (raw) In-Reply-To: <20190729115544.17895-14-anup.patel@wdc.com> On 29/07/19 13:57, Anup Patel wrote: > + if (delta_ns > VCPU_TIMER_PROGRAM_THRESHOLD_NS) { > + hrtimer_start(&t->hrt, ktime_add_ns(ktime_get(), delta_ns), I think the guest would prefer if you saved the time before enabling interrupts on the host, and use that here instead of ktime_get(). Otherwise the timer could be delayed arbitrarily by host interrupts. (Because the RISC-V SBI timer is relative only---which is unfortunate---guests will already pay a latency price due to the extra cost of the SBI call compared to a bare metal implementation. Sooner or later you may want to implement something like x86's heuristic to advance the timer deadline by a few hundred nanoseconds; perhaps add a TODO now). Paolo > + HRTIMER_MODE_ABS); > + t->is_set = true; > + } else > + kvm_riscv_vcpu_set_interrupt(vcpu, IRQ_S_TIMER); > +
WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com> To: Anup Patel <Anup.Patel@wdc.com>, Palmer Dabbelt <palmer@sifive.com>, Paul Walmsley <paul.walmsley@sifive.com>, Radim K <rkrcmar@redhat.com> Cc: Damien Le Moal <Damien.LeMoal@wdc.com>, "kvm@vger.kernel.org" <kvm@vger.kernel.org>, Anup Patel <anup@brainfault.org>, Daniel Lezcano <daniel.lezcano@linaro.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Christoph Hellwig <hch@infradead.org>, Atish Patra <Atish.Patra@wdc.com>, Alistair Francis <Alistair.Francis@wdc.com>, Thomas Gleixner <tglx@linutronix.de>, "linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org> Subject: Re: [RFC PATCH 13/16] RISC-V: KVM: Add timer functionality Date: Tue, 30 Jul 2019 13:26:38 +0200 [thread overview] Message-ID: <abedb067-b91f-8821-9bce-d27f6c4efdee@redhat.com> (raw) In-Reply-To: <20190729115544.17895-14-anup.patel@wdc.com> On 29/07/19 13:57, Anup Patel wrote: > + if (delta_ns > VCPU_TIMER_PROGRAM_THRESHOLD_NS) { > + hrtimer_start(&t->hrt, ktime_add_ns(ktime_get(), delta_ns), I think the guest would prefer if you saved the time before enabling interrupts on the host, and use that here instead of ktime_get(). Otherwise the timer could be delayed arbitrarily by host interrupts. (Because the RISC-V SBI timer is relative only---which is unfortunate---guests will already pay a latency price due to the extra cost of the SBI call compared to a bare metal implementation. Sooner or later you may want to implement something like x86's heuristic to advance the timer deadline by a few hundred nanoseconds; perhaps add a TODO now). Paolo > + HRTIMER_MODE_ABS); > + t->is_set = true; > + } else > + kvm_riscv_vcpu_set_interrupt(vcpu, IRQ_S_TIMER); > + _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2019-07-30 11:26 UTC|newest] Thread overview: 134+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-07-29 11:56 [RFC PATCH 00/16] KVM RISC-V Support Anup Patel 2019-07-29 11:56 ` Anup Patel 2019-07-29 11:56 ` [RFC PATCH 01/16] KVM: RISC-V: Add KVM_REG_RISCV for ONE_REG interface Anup Patel 2019-07-29 11:56 ` Anup Patel 2019-07-29 11:56 ` [RFC PATCH 02/16] RISC-V: Add hypervisor extension related CSR defines Anup Patel 2019-07-29 11:56 ` Anup Patel 2019-07-29 11:56 ` [RFC PATCH 03/16] RISC-V: Add initial skeletal KVM support Anup Patel 2019-07-29 11:56 ` Anup Patel 2019-07-30 9:23 ` Paolo Bonzini 2019-07-30 9:23 ` Paolo Bonzini 2019-07-30 11:04 ` Anup Patel 2019-07-30 11:04 ` Anup Patel 2019-07-30 9:25 ` Paolo Bonzini 2019-07-30 9:25 ` Paolo Bonzini 2019-07-30 11:03 ` Anup Patel 2019-07-30 11:03 ` Anup Patel 2019-07-29 11:56 ` [RFC PATCH 04/16] RISC-V: KVM: Implement VCPU create, init and destroy functions Anup Patel 2019-07-29 11:56 ` Anup Patel 2019-07-30 8:48 ` Paolo Bonzini 2019-07-30 8:48 ` Paolo Bonzini 2019-07-30 10:16 ` Paolo Bonzini 2019-07-30 10:16 ` Paolo Bonzini 2019-07-30 11:45 ` Anup Patel 2019-07-30 11:45 ` Anup Patel 2019-07-30 11:47 ` Paolo Bonzini 2019-07-30 11:47 ` Paolo Bonzini 2019-07-29 11:56 ` [RFC PATCH 05/16] RISC-V: KVM: Implement VCPU interrupts and requests handling Anup Patel 2019-07-29 11:56 ` Anup Patel 2019-07-30 11:17 ` Paolo Bonzini 2019-07-30 11:17 ` Paolo Bonzini 2019-07-30 12:00 ` Anup Patel 2019-07-30 12:00 ` Anup Patel 2019-07-30 12:12 ` Paolo Bonzini 2019-07-30 12:12 ` Paolo Bonzini 2019-07-30 12:45 ` Anup Patel 2019-07-30 12:45 ` Anup Patel 2019-07-30 13:18 ` Paolo Bonzini 2019-07-30 13:18 ` Paolo Bonzini 2019-07-30 13:35 ` Anup Patel 2019-07-30 13:35 ` Anup Patel 2019-07-30 14:08 ` Paolo Bonzini 2019-07-30 14:08 ` Paolo Bonzini 2019-08-02 3:59 ` Anup Patel 2019-08-02 3:59 ` Anup Patel 2019-07-29 11:56 ` [RFC PATCH 06/16] RISC-V: KVM: Implement KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls Anup Patel 2019-07-29 11:56 ` Anup Patel 2019-07-30 8:43 ` Paolo Bonzini 2019-07-30 8:43 ` Paolo Bonzini 2019-07-30 9:35 ` Paolo Bonzini 2019-07-30 9:35 ` Paolo Bonzini 2019-07-30 12:08 ` Anup Patel 2019-07-30 12:08 ` Anup Patel 2019-07-30 12:10 ` Paolo Bonzini 2019-07-30 12:10 ` Paolo Bonzini 2019-07-30 12:16 ` Anup Patel 2019-07-30 12:16 ` Anup Patel 2019-07-29 11:57 ` [RFC PATCH 07/16] RISC-V: KVM: Implement VCPU world-switch Anup Patel 2019-07-29 11:57 ` Anup Patel 2019-07-30 9:34 ` Paolo Bonzini 2019-07-30 9:34 ` Paolo Bonzini 2019-07-30 12:51 ` Anup Patel 2019-07-30 12:51 ` Anup Patel 2019-07-29 11:57 ` [RFC PATCH 08/16] RISC-V: KVM: Handle MMIO exits for VCPU Anup Patel 2019-07-29 11:57 ` Anup Patel 2019-07-30 11:20 ` Paolo Bonzini 2019-07-30 11:20 ` Paolo Bonzini 2019-07-31 7:23 ` Anup Patel 2019-07-31 7:23 ` Anup Patel 2019-07-29 11:57 ` [RFC PATCH 09/16] RISC-V: KVM: Handle WFI " Anup Patel 2019-07-29 11:57 ` Anup Patel 2019-07-29 11:57 ` [RFC PATCH 10/16] RISC-V: KVM: Implement VMID allocator Anup Patel 2019-07-29 11:57 ` Anup Patel 2019-07-30 8:59 ` Paolo Bonzini 2019-07-30 8:59 ` Paolo Bonzini 2019-07-29 11:57 ` [RFC PATCH 11/16] RISC-V: KVM: Implement stage2 page table programming Anup Patel 2019-07-29 11:57 ` Anup Patel 2019-07-30 9:00 ` Paolo Bonzini 2019-07-30 9:00 ` Paolo Bonzini 2019-07-30 12:14 ` Anup Patel 2019-07-30 12:14 ` Anup Patel 2019-07-29 11:57 ` [RFC PATCH 12/16] RISC-V: KVM: Implement MMU notifiers Anup Patel 2019-07-29 11:57 ` Anup Patel 2019-07-29 11:57 ` [RFC PATCH 13/16] RISC-V: KVM: Add timer functionality Anup Patel 2019-07-29 11:57 ` Anup Patel 2019-07-29 14:40 ` Andreas Schwab 2019-07-29 14:40 ` Andreas Schwab 2019-07-29 18:02 ` Atish Patra 2019-07-29 18:02 ` Atish Patra 2019-07-30 6:51 ` Andreas Schwab 2019-07-30 6:51 ` Andreas Schwab 2019-07-30 7:00 ` Atish Patra 2019-07-30 7:00 ` Atish Patra 2019-07-30 11:26 ` Paolo Bonzini [this message] 2019-07-30 11:26 ` Paolo Bonzini 2019-07-31 1:55 ` Atish Patra 2019-07-31 1:55 ` Atish Patra 2019-07-31 6:58 ` Paolo Bonzini 2019-07-31 6:58 ` Paolo Bonzini 2019-07-31 7:18 ` Anup Patel 2019-07-31 7:18 ` Anup Patel 2019-07-29 11:57 ` [RFC PATCH 14/16] RISC-V: KVM: FP lazy save/restore Anup Patel 2019-07-29 11:57 ` Anup Patel 2019-07-29 11:57 ` [RFC PATCH 15/16] RISC-V: KVM: Add SBI v0.1 support Anup Patel 2019-07-29 11:57 ` Anup Patel 2019-07-29 19:40 ` Paolo Bonzini 2019-07-29 19:40 ` Paolo Bonzini 2019-07-29 19:51 ` Atish Patra 2019-07-29 19:51 ` Atish Patra 2019-07-29 20:08 ` Paolo Bonzini 2019-07-29 20:08 ` Paolo Bonzini 2019-07-29 21:08 ` Atish Patra 2019-07-29 21:08 ` Atish Patra 2019-07-30 9:26 ` Paolo Bonzini 2019-07-30 9:26 ` Paolo Bonzini 2019-07-29 11:58 ` [RFC PATCH 16/16] RISC-V: Enable VIRTIO drivers in RV64 and RV32 defconfig Anup Patel 2019-07-29 11:58 ` Anup Patel 2019-07-29 21:47 ` [RFC PATCH 00/16] KVM RISC-V Support Paolo Bonzini 2019-07-29 21:47 ` Paolo Bonzini 2019-07-30 5:26 ` Anup Patel 2019-07-30 5:26 ` Anup Patel 2019-07-30 11:33 ` Paolo Bonzini 2019-07-30 11:33 ` Paolo Bonzini 2019-07-30 13:50 ` Anup Patel 2019-07-30 13:50 ` Anup Patel 2019-07-30 14:02 ` Paolo Bonzini 2019-07-30 14:02 ` Paolo Bonzini 2019-07-30 6:53 ` Andreas Schwab 2019-07-30 6:53 ` Andreas Schwab 2019-07-30 7:25 ` Anup Patel 2019-07-30 7:25 ` Anup Patel 2019-07-30 7:42 ` Andreas Schwab 2019-07-30 7:42 ` Andreas Schwab 2019-07-30 7:36 ` Anup Patel 2019-07-30 7:36 ` Anup Patel
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