summaryrefslogtreecommitdiff
path: root/drivers/irqchip
diff options
context:
space:
mode:
authorAlexandru Elisei <alexandru.elisei@arm.com>2020-09-12 18:37:07 +0300
committerMarc Zyngier <maz@kernel.org>2020-09-13 19:52:04 +0300
commit336780590990efa69596884114cad3f517b6333b (patch)
tree7476d504610b041dfeb517d447ff5022b9073e84 /drivers/irqchip
parent4e594ad1068ea1db359d6161f580f03edecf6cb0 (diff)
downloadlinux-336780590990efa69596884114cad3f517b6333b.tar.xz
irqchip/gic-v3: Support pseudo-NMIs when SCR_EL3.FIQ == 0
The GIC's internal view of the priority mask register and the assigned interrupt priorities are based on whether GIC security is enabled and whether firmware routes Group 0 interrupts to EL3. At the moment, we support priority masking when ICC_PMR_EL1 and interrupt priorities are either both modified by the GIC, or both left unchanged. Trusted Firmware-A's default interrupt routing model allows Group 0 interrupts to be delivered to the non-secure world (SCR_EL3.FIQ == 0). Unfortunately, this is precisely the case that the GIC driver doesn't support: ICC_PMR_EL1 remains unchanged, but the GIC's view of interrupt priorities is different from the software programmed values. Support pseudo-NMIs when SCR_EL3.FIQ == 0 by using a different value to mask regular interrupts. All the other values remain the same. Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20200912153707.667731-3-alexandru.elisei@arm.com
Diffstat (limited to 'drivers/irqchip')
-rw-r--r--drivers/irqchip/irq-gic-v3.c56
1 files changed, 44 insertions, 12 deletions
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index aa9b43d412b2..bb55d89d7d49 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -75,16 +75,14 @@ static DEFINE_STATIC_KEY_TRUE(supports_deactivate_key);
*
* If SCR_EL3.FIQ == 1, the values writen to/read from PMR and RPR at non-secure
* EL1 are subject to a similar operation thus matching the priorities presented
- * from the (re)distributor when security is enabled.
+ * from the (re)distributor when security is enabled. When SCR_EL3.FIQ == 0,
+ * these values are unchanched by the GIC.
*
* see GICv3/GICv4 Architecture Specification (IHI0069D):
* - section 4.8.1 Non-secure accesses to register fields for Secure interrupt
* priorities.
* - Figure 4-7 Secure read of the priority field for a Non-secure Group 1
* interrupt.
- *
- * For now, we only support pseudo-NMIs if we have non-secure view of
- * priorities.
*/
static DEFINE_STATIC_KEY_FALSE(supports_pseudo_nmis);
@@ -97,6 +95,9 @@ static DEFINE_STATIC_KEY_FALSE(supports_pseudo_nmis);
DEFINE_STATIC_KEY_FALSE(gic_pmr_sync);
EXPORT_SYMBOL(gic_pmr_sync);
+DEFINE_STATIC_KEY_FALSE(gic_nonsecure_priorities);
+EXPORT_SYMBOL(gic_nonsecure_priorities);
+
/* ppi_nmi_refs[n] == number of cpus having ppi[n + 16] set as NMI */
static refcount_t *ppi_nmi_refs;
@@ -932,14 +933,20 @@ static void gic_cpu_sys_reg_init(void)
/* Set priority mask register */
if (!gic_prio_masking_enabled()) {
write_gicreg(DEFAULT_PMR_VALUE, ICC_PMR_EL1);
- } else {
+ } else if (gic_supports_nmi()) {
/*
* Mismatch configuration with boot CPU, the system is likely
* to die as interrupt masking will not work properly on all
* CPUs
+ *
+ * The boot CPU calls this function before enabling NMI support,
+ * and as a result we'll never see this warning in the boot path
+ * for that CPU.
*/
- WARN_ON(gic_supports_nmi() && group0 &&
- !gic_dist_security_disabled());
+ if (static_branch_unlikely(&gic_nonsecure_priorities))
+ WARN_ON(!group0 || gic_dist_security_disabled());
+ else
+ WARN_ON(group0 && !gic_dist_security_disabled());
}
/*
@@ -1544,11 +1551,6 @@ static void gic_enable_nmi_support(void)
if (!gic_prio_masking_enabled())
return;
- if (gic_has_group0() && !gic_dist_security_disabled()) {
- pr_warn("SCR_EL3.FIQ is cleared, cannot enable use of pseudo-NMIs\n");
- return;
- }
-
ppi_nmi_refs = kcalloc(gic_data.ppi_nr, sizeof(*ppi_nmi_refs), GFP_KERNEL);
if (!ppi_nmi_refs)
return;
@@ -1567,6 +1569,36 @@ static void gic_enable_nmi_support(void)
pr_info("Pseudo-NMIs enabled using %s ICC_PMR_EL1 synchronisation\n",
static_branch_unlikely(&gic_pmr_sync) ? "forced" : "relaxed");
+ /*
+ * How priority values are used by the GIC depends on two things:
+ * the security state of the GIC (controlled by the GICD_CTRL.DS bit)
+ * and if Group 0 interrupts can be delivered to Linux in the non-secure
+ * world as FIQs (controlled by the SCR_EL3.FIQ bit). These affect the
+ * the ICC_PMR_EL1 register and the priority that software assigns to
+ * interrupts:
+ *
+ * GICD_CTRL.DS | SCR_EL3.FIQ | ICC_PMR_EL1 | Group 1 priority
+ * -----------------------------------------------------------
+ * 1 | - | unchanged | unchanged
+ * -----------------------------------------------------------
+ * 0 | 1 | non-secure | non-secure
+ * -----------------------------------------------------------
+ * 0 | 0 | unchanged | non-secure
+ *
+ * where non-secure means that the value is right-shifted by one and the
+ * MSB bit set, to make it fit in the non-secure priority range.
+ *
+ * In the first two cases, where ICC_PMR_EL1 and the interrupt priority
+ * are both either modified or unchanged, we can use the same set of
+ * priorities.
+ *
+ * In the last case, where only the interrupt priorities are modified to
+ * be in the non-secure range, we use a different PMR value to mask IRQs
+ * and the rest of the values that we use remain unchanged.
+ */
+ if (gic_has_group0() && !gic_dist_security_disabled())
+ static_branch_enable(&gic_nonsecure_priorities);
+
static_branch_enable(&supports_pseudo_nmis);
if (static_branch_likely(&supports_deactivate_key))