Commit 80e9963f authored Apr 06, 2024 by Nianyao Tang Committed by Thomas Gleixner Apr 09, 2024

irqchip/gic-v3-its: Fix VSYNC referencing an unmapped VPE on GIC v4.1



As per the GICv4.1 spec (Arm IHI 0069H, 5.3.19):

 "A VMAPP with {V, Alloc}=={0, x} is self-synchronizing, This means the ITS
  command queue does not show the command as consumed until all of its
  effects are completed."

Furthermore, VSYNC is allowed to deliver an SError when referencing a
non existent VPE.

By these definitions, a VMAPP followed by a VSYNC is a bug, as the
later references a VPE that has been unmapped by the former.

Fix it by eliding the VSYNC in this scenario.

Fixes: 64edfaa9 ("irqchip/gic-v4.1: Implement the v4.1 flavour of VMAPP")
Signed-off-by: Nianyao Tang <tangnianyao@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Link: https://lore.kernel.org/r/20240406022737.3898763-1-tangnianyao@huawei.com

parent fec50db7

drivers/irqchip/irq-gic-v3-its.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -786,6 +786,7 @@ static struct its_vpe its_build_vmapp_cmd(struct its_node its,
		struct its_cmd_block *cmd,
		struct its_cmd_desc *desc)
		{
		struct its_vpe *vpe = valid_vpe(its, desc->its_vmapp_cmd.vpe);
		unsigned long vpt_addr, vconf_addr;
		u64 target;
		bool alloc;
		@@ -798,6 +799,11 @@ static struct its_vpe its_build_vmapp_cmd(struct its_node its,
		if (is_v4_1(its)) {
		alloc = !atomic_dec_return(&desc->its_vmapp_cmd.vpe->vmapp_count);
		its_encode_alloc(cmd, alloc);
		/*
		* Unmapping a VPE is self-synchronizing on GICv4.1,
		* no need to issue a VSYNC.
		*/
		vpe = NULL;
		}

		goto out;
		@@ -832,7 +838,7 @@ static struct its_vpe its_build_vmapp_cmd(struct its_node its,
		out:
		its_fixup_cmd(cmd);

		return valid_vpe(its, desc->its_vmapp_cmd.vpe);
		return vpe;
		}

		static struct its_vpe its_build_vmapti_cmd(struct its_node its,