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Thu, 19 Mar 2020 10:55:59 +0000 MIME-Version: 1.0 Date: Thu, 19 Mar 2020 10:55:59 +0000 From: Marc Zyngier To: Zenghui Yu Subject: Re: [PATCH v5 16/23] irqchip/gic-v4.1: Eagerly vmap vPEs In-Reply-To: <2817cb89-4cc2-549f-6e40-91d941aa8a5f@huawei.com> References: <20200304203330.4967-1-maz@kernel.org> <20200304203330.4967-17-maz@kernel.org> <2817cb89-4cc2-549f-6e40-91d941aa8a5f@huawei.com> Message-ID: X-Sender: maz@kernel.org User-Agent: Roundcube Webmail/1.3.10 X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: yuzenghui@huawei.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, lorenzo.pieralisi@arm.com, jason@lakedaemon.net, rrichter@marvell.com, tglx@linutronix.de, eric.auger@redhat.com, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200319_035601_951869_28CE9E07 X-CRM114-Status: GOOD ( 17.60 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Lorenzo Pieralisi , Jason Cooper , kvm@vger.kernel.org, Suzuki K Poulose , linux-kernel@vger.kernel.org, Eric Auger , Robert Richter , James Morse , Julien Thierry , Thomas Gleixner , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2020-03-17 02:49, Zenghui Yu wrote: > Hi Marc, > > On 2020/3/5 4:33, Marc Zyngier wrote: >> Now that we have HW-accelerated SGIs being delivered to VPEs, it >> becomes required to map the VPEs on all ITSs instead of relying >> on the lazy approach that we would use when using the ITS-list >> mechanism. >> >> Signed-off-by: Marc Zyngier > > Before GICv4.1, we use vlpi_count to evaluate whether the vPE has been > mapped on the specified ITS, and use this refcount to only issue VMOVP > to those involved ITSes. It's broken after this patch. > > We may need to re-evaluate "whether the vPE is mapped" now that we're > at > GICv4.1, otherwise *no* VMOVP will be issued on the v4.1 capable > machine > (I mean those without single VMOVP support). > > What I'm saying is something like below (only an idea, it even can't > compile), any thoughts? > > > diff --git a/drivers/irqchip/irq-gic-v3-its.c > b/drivers/irqchip/irq-gic-v3-its.c > index 2e12bc52e3a2..3450b5e847ca 100644 > --- a/drivers/irqchip/irq-gic-v3-its.c > +++ b/drivers/irqchip/irq-gic-v3-its.c > @@ -198,7 +198,8 @@ static u16 get_its_list(struct its_vm *vm) > if (!is_v4(its)) > continue; > > - if (vm->vlpi_count[its->list_nr]) > + if (vm->vlpi_count[its->list_nr] || > + gic_requires_eager_mapping()) > __set_bit(its->list_nr, &its_list); > } > > @@ -1295,7 +1296,8 @@ static void its_send_vmovp(struct its_vpe *vpe) > if (!is_v4(its)) > continue; > > - if (!vpe->its_vm->vlpi_count[its->list_nr]) > + if (!vpe->its_vm->vlpi_count[its->list_nr] && > + !gic_requires_eager_mapping()) > continue; > > desc.its_vmovp_cmd.col = &its->collections[col_id]; It took me a while to wrap my head around that one, but you're as usual spot on. The use of gic_requires_eager_mapping() is a bit confusing here, as it isn't so much that the VPE is eagerly mapped, but the predicate on which we evaluate the need for a VMOVP. How about this: diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index cd6451e190c9..348f7a909a69 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -189,6 +189,15 @@ static DEFINE_IDA(its_vpeid_ida); #define gic_data_rdist_rd_base() (gic_data_rdist()->rd_base) #define gic_data_rdist_vlpi_base() (gic_data_rdist_rd_base() + SZ_128K) +/* + * Skip ITSs that have no vLPIs mapped, unless we're on GICv4.1, as we + * always have vSGIs mapped. + */ +static bool require_its_list_vmovp(struct its_vm *vm, struct its_node *its) +{ + return (gic_rdists->has_rvpeid || vm->vlpi_count[its->list_nr]); +} + static u16 get_its_list(struct its_vm *vm) { struct its_node *its; @@ -198,7 +207,7 @@ static u16 get_its_list(struct its_vm *vm) if (!is_v4(its)) continue; - if (vm->vlpi_count[its->list_nr]) + if (require_its_list_vmovp(vm, its)) __set_bit(its->list_nr, &its_list); } @@ -1295,7 +1304,7 @@ static void its_send_vmovp(struct its_vpe *vpe) if (!is_v4(its)) continue; - if (!vpe->its_vm->vlpi_count[its->list_nr]) + if (!require_its_list_vmovp(vpe->its_vm, its)) continue; desc.its_vmovp_cmd.col = &its->collections[col_id]; Thanks, M. -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel