6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Marc Zyngier <maz@xxxxxxxxxx>
commit 1442ee0011983f0c5c4b92380e6853afb513841a upstream.
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@xxxxxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/c182ece6-2ba0-ce4f-3404-dba7a3ab6c52@xxxxxxxxxx
Link: https://lore.kernel.org/all/20241002204959.2051709-1-maz@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/irqchip/irq-gic-v3-its.c | 18 ++++++++++++------
include/linux/irqchip/arm-gic-v4.h | 4 +++-
2 files changed, 15 insertions(+), 7 deletions(-)
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -796,8 +796,8 @@ static struct its_vpe *its_build_vmapp_c
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,
@@ -816,13 +816,13 @@ static struct its_vpe *its_build_vmapp_c
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);
/*
@@ -3817,6 +3817,13 @@ static int its_vpe_set_affinity(struct i
int from, cpu;
/*
+ * 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
@@ -4456,9 +4463,8 @@ static int its_vpe_init(struct its_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;
--- a/include/linux/irqchip/arm-gic-v4.h
+++ b/include/linux/irqchip/arm-gic-v4.h
@@ -58,10 +58,12 @@ 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.
