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

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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: 64edfaa9a2 ("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
This commit is contained in:
Marc Zyngier 2024-10-02 21:49:59 +01:00 committed by Thomas Gleixner
parent 6eabf65604
commit 1442ee0011
2 changed files with 15 additions and 7 deletions
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18
drivers/irqchip/irq-gic-v3-its.c
View File

@ -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);
/*
@ -3806,6 +3806,13 @@ static int its_vpe_set_affinity(struct irq_data *d,
struct cpumask *table_mask;
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
@ -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;

4
include/linux/irqchip/arm-gic-v4.h
View File

@ -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.