diff options
author | Alexandru Elisei <alexandru.elisei@arm.com> | 2020-09-12 16:37:07 +0100 |
---|---|---|
committer | Marc Zyngier <maz@kernel.org> | 2020-09-13 17:52:04 +0100 |
commit | 336780590990efa69596884114cad3f517b6333b (patch) | |
tree | 7476d504610b041dfeb517d447ff5022b9073e84 /drivers | |
parent | 4e594ad1068ea1db359d6161f580f03edecf6cb0 (diff) |
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')
-rw-r--r-- | drivers/irqchip/irq-gic-v3.c | 56 |
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)) |