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From: Marc Zyngier <maz@kernel.org>
To: Zenghui Yu <yuzenghui@huawei.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Jason Cooper <jason@lakedaemon.net>,
	linux-kernel@vger.kernel.org,
	Robert Richter <rrichter@marvell.com>,
	Jayachandran C <jnair@marvell.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH v2 03/36] irqchip/gic-v3-its: Allow LPI invalidation via the DirectLPI interface
Date: Fri, 01 Nov 2019 13:26:37 +0000
Message-ID: <86ftj7ybg2.wl-maz@kernel.org> (raw)
In-Reply-To: <a263e264-298c-57cf-31b7-a781160a3929@huawei.com>

On Thu, 31 Oct 2019 08:49:32 +0000,
Zenghui Yu <yuzenghui@huawei.com> wrote:
> 
> Hi Marc,
> 
> On 2019/10/27 22:42, Marc Zyngier wrote:
> > We currently don't make much use of the DirectLPI feature, and it would
> > be beneficial to do this more, if only because it becomes a mandatory
> > feature for GICv4.1.
> > 
> > Signed-off-by: Marc Zyngier <maz@kernel.org>
> 
> I have no objection to this patch, which says:
> 
> Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
> 
> 
> But this patch really drives me to look through all callsites of
> dev_event_to_col(), the abstraction which can be used _only_ with
> physical LPI mappings.
> 
> I find that when building the INV command, we use dev_event_to_col()
> to find the "sync_obj" and then pass it to the following SYNC command.
> But the "INV+SYNC" will be performed both on physical LPI and *VLPI*
> (lpi_update_config/its_send_inv).
> So I have two questions about the way we sending INV on VLPI:
> 
> 1) Which "sync" command should be followed?  SYNC or VSYNC?
> (we currently use SYNC, while the spec says, SYNC "ensures all
> outstanding ITS operations associated with *physical* interrupts
> for the Redistributor are globally observed ...")
> 
> 2) The "sync_obj" we are currently using seems to be wrong.

I think you're right on both counts (where were you when I wrote the
initial GICv4 support? ;-). I think the confusion stems from the fact
that there is no 'VINV' command, and we simply overlooked the sync
object issue. It is quite likely that existing implementations don't
care much about the difference (otherwise we'd have seen the problem
before), but it doesn't hurt to do the right thing.

I have the following patch as part of a set of fixes that I'm about to
post (once I get a chance to test them), let me know what you think.

	M.

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index a47ed2ba2907..75ab3716a870 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -702,6 +702,24 @@ static struct its_vpe *its_build_vmovp_cmd(struct its_node *its,
 	return valid_vpe(its, desc->its_vmovp_cmd.vpe);
 }
 
+static struct its_vpe *its_build_vinv_cmd(struct its_node *its,
+					  struct its_cmd_block *cmd,
+					  struct its_cmd_desc *desc)
+{
+	struct its_vlpi_map *map;
+
+	map = dev_event_to_vlpi_map(desc->its_inv_cmd.dev,
+				    desc->its_inv_cmd.event_id);
+
+	its_encode_cmd(cmd, GITS_CMD_INV);
+	its_encode_devid(cmd, desc->its_inv_cmd.dev->device_id);
+	its_encode_event_id(cmd, desc->its_inv_cmd.event_id);
+
+	its_fixup_cmd(cmd);
+
+	return valid_vpe(its, map->vpe);
+}
+
 static u64 its_cmd_ptr_to_offset(struct its_node *its,
 				 struct its_cmd_block *ptr)
 {
@@ -1068,6 +1086,20 @@ static void its_send_vinvall(struct its_node *its, struct its_vpe *vpe)
 	its_send_single_vcommand(its, its_build_vinvall_cmd, &desc);
 }
 
+static void its_send_vinv(struct its_device *dev, u32 event_id)
+{
+	struct its_cmd_desc desc;
+
+	/*
+	 * There is no real VINV command. This is just a normal INV,
+	 * with a VSYNC instead of a SYNC.
+	 */
+	desc.its_inv_cmd.dev = dev;
+	desc.its_inv_cmd.event_id = event_id;
+
+	its_send_single_vcommand(dev->its, its_build_vinv_cmd, &desc);
+}
+
 /*
  * irqchip functions - assumes MSI, mostly.
  */
@@ -1142,8 +1174,10 @@ static void lpi_update_config(struct irq_data *d, u8 clr, u8 set)
 	lpi_write_config(d, clr, set);
 	if (gic_rdists->has_direct_lpi && !irqd_is_forwarded_to_vcpu(d))
 		direct_lpi_inv(d);
-	else
+	else if (!irqd_is_forwarded_to_vcpu(d))
 		its_send_inv(its_dev, its_get_event_id(d));
+	else
+		its_send_vinv(its_dev, its_get_event_id(d));
 }
 
 static void its_vlpi_set_doorbell(struct irq_data *d, bool enable)

-- 
Jazz is not dead, it just smells funny.
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Thread overview: 65+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-27 14:41 [PATCH v2 00/36] irqchip/gic-v4: GICv4.1 architecture support Marc Zyngier
2019-10-27 14:41 ` [PATCH v2 01/36] KVM: arm64: vgic-v4: Move the GICv4 residency flow to be driven by vcpu_load/put Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 02/36] irqchip/gic-v3-its: Factor out wait_for_syncr primitive Marc Zyngier
2019-10-28  9:20   ` Zenghui Yu
2019-10-27 14:42 ` [PATCH v2 03/36] irqchip/gic-v3-its: Allow LPI invalidation via the DirectLPI interface Marc Zyngier
2019-10-31  8:49   ` Zenghui Yu
2019-11-01 13:26     ` Marc Zyngier [this message]
2019-11-05 10:30       ` Zenghui Yu
2019-11-05 12:12         ` Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 04/36] irqchip/gic-v3-its: Make is_v4 use a TYPER copy Marc Zyngier
2019-10-28  9:34   ` Zenghui Yu
2019-10-28 10:52     ` Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 05/36] irqchip/gic-v3-its: Kill its->ite_size and use TYPER copy instead Marc Zyngier
2019-10-28  9:40   ` Zenghui Yu
2019-10-27 14:42 ` [PATCH v2 06/36] irqchip/gic-v3-its: Kill its->device_ids " Marc Zyngier
2019-10-31  6:33   ` Zenghui Yu
2019-10-31  8:30     ` Marc Zyngier
2019-10-31  9:08       ` Zenghui Yu
2019-10-27 14:42 ` [PATCH v2 07/36] irqchip/gic-v3-its: Add get_vlpi_map() helper Marc Zyngier
2019-10-31  3:54   ` Zenghui Yu
2019-10-27 14:42 ` [PATCH v2 08/36] irqchip/gic-v3: Detect GICv4.1 supporting RVPEID Marc Zyngier
2019-10-31 11:34   ` Zenghui Yu
2019-10-27 14:42 ` [PATCH v2 09/36] irqchip/gic-v3: Add GICv4.1 VPEID size discovery Marc Zyngier
2019-10-31 12:02   ` Zenghui Yu
2019-11-01 15:13     ` Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 10/36] irqchip/gic-v3: Workaround Cavium TX1 erratum when reading GICD_TYPER2 Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 11/36] irqchip/gic-v4.1: VPE table (aka GICR_VPROPBASER) allocation Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 12/36] irqchip/gic-v4.1: Implement the v4.1 flavour of VMAPP Marc Zyngier
2019-11-01 10:58   ` Zenghui Yu
2019-11-13  8:02   ` Zenghui Yu
2019-11-13  9:47     ` Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 13/36] irqchip/gic-v4.1: Don't use the VPE proxy if RVPEID is set Marc Zyngier
2019-11-01 11:05   ` Zenghui Yu
2019-10-27 14:42 ` [PATCH v2 14/36] irqchip/gic-v4.1: Implement the v4.1 flavour of VMOVP Marc Zyngier
2019-11-01 11:10   ` Zenghui Yu
2019-10-27 14:42 ` [PATCH v2 15/36] irqchip/gic-v4.1: Plumb skeletal VPE irqchip Marc Zyngier
2019-11-01 11:13   ` Zenghui Yu
2019-10-27 14:42 ` [PATCH v2 16/36] irqchip/gic-v4.1: Add mask/unmask doorbell callbacks Marc Zyngier
2019-11-01 11:23   ` Zenghui Yu
2019-10-27 14:42 ` [PATCH v2 17/36] irqchip/gic-v4.1: Add VPE residency callback Marc Zyngier
2019-11-01 11:34   ` Zenghui Yu
2019-10-27 14:42 ` [PATCH v2 18/36] irqchip/gic-v4.1: Add VPE eviction callback Marc Zyngier
2019-11-01 11:39   ` Zenghui Yu
2019-10-27 14:42 ` [PATCH v2 19/36] irqchip/gic-v4.1: Add VPE INVALL callback Marc Zyngier
2019-11-01 11:51   ` Zenghui Yu
2019-10-27 14:42 ` [PATCH v2 20/36] irqchip/gic-v4.1: Suppress per-VLPI doorbell Marc Zyngier
2019-11-01 12:17   ` Zenghui Yu
2019-10-27 14:42 ` [PATCH v2 21/36] irqchip/gic-v4.1: Allow direct invalidation of VLPIs Marc Zyngier
2019-11-01 12:30   ` Zenghui Yu
2019-10-27 14:42 ` [PATCH v2 22/36] irqchip/gic-v4.1: Advertise support v4.1 to KVM Marc Zyngier
2019-11-01 12:55   ` Zenghui Yu
2019-10-27 14:42 ` [PATCH v2 23/36] irqchip/gic-v4.1: Map the ITS SGIR register page Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 24/36] irqchip/gic-v4.1: Plumb skeletal VSGI irqchip Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 25/36] irqchip/gic-v4.1: Add initial SGI configuration Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 26/36] irqchip/gic-v4.1: Plumb mask/unmask SGI callbacks Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 27/36] irqchip/gic-v4.1: Plumb get/set_irqchip_state " Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 28/36] irqchip/gic-v4.1: Plumb set_vcpu_affinity " Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 29/36] irqchip/gic-v4.1: Move doorbell management to the GICv4 abstraction layer Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 30/36] irqchip/gic-v4.1: Add VSGI allocation/teardown Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 31/36] irqchip/gic-v4.1: Add VSGI property setup Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 32/36] irqchip/gic-v4.1: Eagerly vmap vPEs Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 33/36] KVM: arm64: GICv4.1: Let doorbells be auto-enabled Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 34/36] KVM: arm64: GICv4.1: Add direct injection capability to SGI registers Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 35/36] KVM: arm64: GICv4.1: Configure SGIs as HW interrupts Marc Zyngier
2019-10-27 14:42 ` [PATCH v2 36/36] KVM: arm64: GICv4.1: Expose HW-based SGIs in debugfs Marc Zyngier

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