The following commit has been merged into the irq/urgent branch of tip:

Commit-ID: 1442ee0011983f0c5c4b92380e6853afb513841a Gitweb: https://git.kernel.org/tip/1442ee0011983f0c5c4b92380e6853afb513841a Author: Marc Zyngier maz@kernel.org AuthorDate: Wed, 02 Oct 2024 21:49:59 +01:00 Committer: Thomas Gleixner tglx@linutronix.de CommitterDate: Tue, 08 Oct 2024 17:44:27 +02:00

irqchip/gic-v4: Don't allow a VMOVP on a dying VPE

Kunkun Jiang reported that there is a small window of opportunity for userspace to force a change of affinity for a VPE while the VPE has already been unmapped, but the corresponding doorbell interrupt still visible in /proc/irq/.

Plug the race by checking the value of vmapp_count, which tracks whether the VPE is mapped ot not, and returning an error in this case.

This involves making vmapp_count common to both GICv4.1 and its v4.0 ancestor.

Fixes: 64edfaa9a234 ("irqchip/gic-v4.1: Implement the v4.1 flavour of VMAPP") Reported-by: Kunkun Jiang jiangkunkun@huawei.com Signed-off-by: Marc Zyngier maz@kernel.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/c182ece6-2ba0-ce4f-3404-dba7a3ab6c52@huawei.com Link: https://lore.kernel.org/all/20241002204959.2051709-1-maz@kernel.org --- drivers/irqchip/irq-gic-v3-its.c | 18 ++++++++++++------ include/linux/irqchip/arm-gic-v4.h | 4 +++- 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index fdec478..ab597e7 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -797,8 +797,8 @@ static struct its_vpe *its_build_vmapp_cmd(struct its_node *its, its_encode_valid(cmd, desc->its_vmapp_cmd.valid);

if (!desc->its_vmapp_cmd.valid) { + alloc = !atomic_dec_return(&desc->its_vmapp_cmd.vpe->vmapp_count); 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, @@ -817,13 +817,13 @@ static struct its_vpe *its_build_vmapp_cmd(struct its_node *its, its_encode_vpt_addr(cmd, vpt_addr); its_encode_vpt_size(cmd, LPI_NRBITS - 1);

+ alloc = !atomic_fetch_inc(&desc->its_vmapp_cmd.vpe->vmapp_count); + if (!is_v4_1(its)) goto out;

vconf_addr = virt_to_phys(page_address(desc->its_vmapp_cmd.vpe->its_vm->vprop_page));

- alloc = !atomic_fetch_inc(&desc->its_vmapp_cmd.vpe->vmapp_count); - its_encode_alloc(cmd, alloc);

/* @@ -3807,6 +3807,13 @@ static int its_vpe_set_affinity(struct irq_data *d, unsigned long flags;

/* + * Check if we're racing against a VPE being destroyed, for + * which we don't want to allow a VMOVP. + */ + if (!atomic_read(&vpe->vmapp_count)) + return -EINVAL; + + /* * Changing affinity is mega expensive, so let's be as lazy as * we can and only do it if we really have to. Also, if mapped * into the proxy device, we need to move the doorbell @@ -4463,9 +4470,8 @@ static int its_vpe_init(struct its_vpe *vpe) raw_spin_lock_init(&vpe->vpe_lock); vpe->vpe_id = vpe_id; vpe->vpt_page = vpt_page; - if (gic_rdists->has_rvpeid) - atomic_set(&vpe->vmapp_count, 0); - else + atomic_set(&vpe->vmapp_count, 0); + if (!gic_rdists->has_rvpeid) vpe->vpe_proxy_event = -1;

return 0; diff --git a/include/linux/irqchip/arm-gic-v4.h b/include/linux/irqchip/arm-gic-v4.h index ecabed6..7f1f11a 100644 --- a/include/linux/irqchip/arm-gic-v4.h +++ b/include/linux/irqchip/arm-gic-v4.h @@ -66,10 +66,12 @@ struct its_vpe { bool enabled; bool group; } sgi_config[16]; - atomic_t vmapp_count; }; };

+ /* Track the VPE being mapped */ + atomic_t vmapp_count; + /* * Ensures mutual exclusion between affinity setting of the * vPE and vLPI operations using vpe->col_idx.