The following commit has been merged into the irq/core branch of tip:
Commit-ID: f0eb154c39471bf881422e8ac23e4c037289ece9
Gitweb: https://git.kernel.org/tip/f0eb154c39471bf881422e8ac23e4c037289ece9
Author: Marc Zyngier <maz@xxxxxxxxxx>
AuthorDate: Fri, 05 Jul 2024 10:31:54 +01:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Mon, 15 Jul 2024 15:13:55 +02:00
irqchip/gic-v4: Substitute vmovp_lock for a per-VM lock
vmovp_lock is abused in a number of cases to serialise updates
to vlpi_count[] and deal with map/unmap of a VM to ITSs.
Instead, provide a per-VM lock and revisit the use of vlpi_count[]
so that it is always wrapped in this per-VM vmapp_lock.
This reduces the potential contention on a concurrent VMOVP command,
and paves the way for subsequent VPE locking that holding vmovp_lock
actively prevents due to the lock ordering.
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Nianyao Tang <tangnianyao@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240705093155.871070-3-maz@xxxxxxxxxx
---
drivers/irqchip/irq-gic-v3-its.c | 27 ++++++++++++---------------
include/linux/irqchip/arm-gic-v4.h | 8 ++++++++
2 files changed, 20 insertions(+), 15 deletions(-)
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 387ac5a..215c7ab 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1317,7 +1317,6 @@ static void its_send_vmovp(struct its_vpe *vpe)
{
struct its_cmd_desc desc = {};
struct its_node *its;
- unsigned long flags;
int col_id = vpe->col_idx;
desc.its_vmovp_cmd.vpe = vpe;
@@ -1330,6 +1329,12 @@ static void its_send_vmovp(struct its_vpe *vpe)
}
/*
+ * Protect against concurrent updates of the mapping state on
+ * individual VMs.
+ */
+ guard(raw_spinlock_irqsave)(&vpe->its_vm->vmapp_lock);
+
+ /*
* Yet another marvel of the architecture. If using the
* its_list "feature", we need to make sure that all ITSs
* receive all VMOVP commands in the same order. The only way
@@ -1337,8 +1342,7 @@ static void its_send_vmovp(struct its_vpe *vpe)
*
* Wall <-- Head.
*/
- raw_spin_lock_irqsave(&vmovp_lock, flags);
-
+ guard(raw_spinlock)(&vmovp_lock);
desc.its_vmovp_cmd.seq_num = vmovp_seq_num++;
desc.its_vmovp_cmd.its_list = get_its_list(vpe->its_vm);
@@ -1353,8 +1357,6 @@ static void its_send_vmovp(struct its_vpe *vpe)
desc.its_vmovp_cmd.col = &its->collections[col_id];
its_send_single_vcommand(its, its_build_vmovp_cmd, &desc);
}
-
- raw_spin_unlock_irqrestore(&vmovp_lock, flags);
}
static void its_send_vinvall(struct its_node *its, struct its_vpe *vpe)
@@ -1791,12 +1793,10 @@ static bool gic_requires_eager_mapping(void)
static void its_map_vm(struct its_node *its, struct its_vm *vm)
{
- unsigned long flags;
-
if (gic_requires_eager_mapping())
return;
- raw_spin_lock_irqsave(&vmovp_lock, flags);
+ guard(raw_spinlock_irqsave)(&vm->vmapp_lock);
/*
* If the VM wasn't mapped yet, iterate over the vpes and get
@@ -1814,19 +1814,15 @@ static void its_map_vm(struct its_node *its, struct its_vm *vm)
its_send_vinvall(its, vpe);
}
}
-
- raw_spin_unlock_irqrestore(&vmovp_lock, flags);
}
static void its_unmap_vm(struct its_node *its, struct its_vm *vm)
{
- unsigned long flags;
-
/* Not using the ITS list? Everything is always mapped. */
if (gic_requires_eager_mapping())
return;
- raw_spin_lock_irqsave(&vmovp_lock, flags);
+ guard(raw_spinlock_irqsave)(&vm->vmapp_lock);
if (!--vm->vlpi_count[its->list_nr]) {
int i;
@@ -1834,8 +1830,6 @@ static void its_unmap_vm(struct its_node *its, struct its_vm *vm)
for (i = 0; i < vm->nr_vpes; i++)
its_send_vmapp(its, vm->vpes[i], false);
}
-
- raw_spin_unlock_irqrestore(&vmovp_lock, flags);
}
static int its_vlpi_map(struct irq_data *d, struct its_cmd_info *info)
@@ -3942,6 +3936,8 @@ static void its_vpe_invall(struct its_vpe *vpe)
{
struct its_node *its;
+ guard(raw_spinlock_irqsave)(&vpe->its_vm->vmapp_lock);
+
list_for_each_entry(its, &its_nodes, entry) {
if (!is_v4(its))
continue;
@@ -4547,6 +4543,7 @@ static int its_vpe_irq_domain_alloc(struct irq_domain *domain, unsigned int virq
vm->db_lpi_base = base;
vm->nr_db_lpis = nr_ids;
vm->vprop_page = vprop_page;
+ raw_spin_lock_init(&vm->vmapp_lock);
if (gic_rdists->has_rvpeid)
irqchip = &its_vpe_4_1_irq_chip;
diff --git a/include/linux/irqchip/arm-gic-v4.h b/include/linux/irqchip/arm-gic-v4.h
index 2c63375..ecabed6 100644
--- a/include/linux/irqchip/arm-gic-v4.h
+++ b/include/linux/irqchip/arm-gic-v4.h
@@ -25,6 +25,14 @@ struct its_vm {
irq_hw_number_t db_lpi_base;
unsigned long *db_bitmap;
int nr_db_lpis;
+ /*
+ * Ensures mutual exclusion between updates to vlpi_count[]
+ * and map/unmap when using the ITSList mechanism.
+ *
+ * The lock order for any sequence involving the ITSList is
+ * vmapp_lock -> vpe_lock ->vmovp_lock.
+ */
+ raw_spinlock_t vmapp_lock;
u32 vlpi_count[GICv4_ITS_LIST_MAX];
};
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