[PATCH 1/3] arm64: Add pseudo NMI support of GICv3 SGIs

[Wei Li]

Currently, only PPIs and SPIs can be set as NMIs. IPIs being currently
hardcoded IRQ numbers, there isn't a generic interface to set SGIs as NMI
for now.

In this patch, we do:
1. Add an interface for setting priority of SGIs.
2. Export GICD_INT_NMI_PRI for setting priority of SGIs as NMI.
3. Move the gic_enable_nmi_support() earlier to make the gic_supports_nmi()
check works in gic_cpu_init().

Signed-off-by: Wei Li <liwei391@xxxxxxxxxx>
Cc: Julien Thierry <julien.thierry@xxxxxxx>
---
 arch/arm64/include/asm/smp.h           |  2 ++
 arch/arm64/kernel/smp.c                |  4 +++
 drivers/irqchip/irq-gic-v3.c           | 46 +++++++++++++++++++++-----
 include/linux/irqchip/arm-gic-common.h |  1 +
 include/linux/irqchip/arm-gic-v3.h     |  1 +
 5 files changed, 45 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index 18553f399e08..84d7ea073d84 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -158,6 +158,8 @@ bool cpus_are_stuck_in_kernel(void);
 extern void crash_smp_send_stop(void);
 extern bool smp_crash_stop_failed(void);
 
+extern void ipi_gic_nmi_setup(void __iomem *base);
+
 #endif /* ifndef __ASSEMBLY__ */
 
 #endif /* ifndef __ASM_SMP_H */
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 824de7038967..bd8fdf6fcd8e 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -1067,3 +1067,7 @@ bool cpus_are_stuck_in_kernel(void)
 
 	return !!cpus_stuck_in_kernel || smp_spin_tables;
 }
+
+void ipi_gic_nmi_setup(void __iomem *base)
+{
+}
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 15e55d327505..394aa5668dd6 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -42,8 +42,6 @@
 
 #include "irq-gic-common.h"
 
-#define GICD_INT_NMI_PRI	(GICD_INT_DEF_PRI & ~0x80)
-
 #define FLAGS_WORKAROUND_GICR_WAKER_MSM8996	(1ULL << 0)
 
 struct redist_region {
@@ -324,6 +322,23 @@ static int gic_irq_get_irqchip_state(struct irq_data *d,
 	return 0;
 }
 
+void gic_sgi_set_prio(void __iomem *base, u32 irqnr, u8 prio)
+{
+	u32 val, offset;
+
+	offset = GICR_IPRIORITYR0 + ((irqnr / 4) * 4);
+
+	/*
+	 * Using writeb here may cause hardware error on some CPUs,
+	 * aovid this quirk by using writel.
+	 */
+	val = readl_relaxed(base + offset);
+	val &= ~(0xff << ((irqnr % 4) * 8));
+	val |= prio << ((irqnr % 4) * 8);
+
+	writel_relaxed(val, base + offset);
+}
+
 static void gic_irq_set_prio(struct irq_data *d, u8 prio)
 {
 	void __iomem *base = gic_dist_base(d);
@@ -474,6 +489,16 @@ static inline void gic_handle_nmi(u32 irqnr, struct pt_regs *regs)
 {
 	int err;
 
+	if (unlikely(irqnr < 16)) {
+		gic_write_eoir(irqnr);
+		if (static_branch_likely(&supports_deactivate_key))
+			gic_write_dir(irqnr);
+#ifdef CONFIG_SMP
+		handle_IPI(irqnr, regs);
+#endif
+		return;
+	}
+
 	if (static_branch_likely(&supports_deactivate_key))
 		gic_write_eoir(irqnr);
 	/*
@@ -859,6 +884,9 @@ static void gic_cpu_init(void)
 
 	gic_cpu_config(rbase, gic_redist_wait_for_rwp);
 
+	if (gic_supports_nmi())
+		ipi_gic_nmi_setup(rbase);
+
 	/* initialise system registers */
 	gic_cpu_sys_reg_init();
 }
@@ -1335,6 +1363,13 @@ static int __init gic_init_bases(void __iomem *dist_base,
 
 	gic_update_vlpi_properties();
 
+	if (gic_prio_masking_enabled()) {
+		if (!gic_has_group0() || gic_dist_security_disabled())
+			gic_enable_nmi_support();
+		else
+			pr_warn("SCR_EL3.FIQ is cleared, cannot enable use of pseudo-NMIs\n");
+	}
+
 	gic_smp_init();
 	gic_dist_init();
 	gic_cpu_init();
@@ -1345,13 +1380,6 @@ static int __init gic_init_bases(void __iomem *dist_base,
 		its_cpu_init();
 	}
 
-	if (gic_prio_masking_enabled()) {
-		if (!gic_has_group0() || gic_dist_security_disabled())
-			gic_enable_nmi_support();
-		else
-			pr_warn("SCR_EL3.FIQ is cleared, cannot enable use of pseudo-NMIs\n");
-	}
-
 	return 0;
 
 out_free:
diff --git a/include/linux/irqchip/arm-gic-common.h b/include/linux/irqchip/arm-gic-common.h
index 9a1a479a2bf4..d8c973295179 100644
--- a/include/linux/irqchip/arm-gic-common.h
+++ b/include/linux/irqchip/arm-gic-common.h
@@ -18,6 +18,7 @@
 					(GICD_INT_DEF_PRI << 16) |\
 					(GICD_INT_DEF_PRI << 8) |\
 					GICD_INT_DEF_PRI)
+#define GICD_INT_NMI_PRI	(GICD_INT_DEF_PRI & ~0x80)
 
 enum gic_type {
 	GIC_V2,
diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
index c848a7cc502e..dc1c418229e7 100644
--- a/include/linux/irqchip/arm-gic-v3.h
+++ b/include/linux/irqchip/arm-gic-v3.h
@@ -606,6 +606,7 @@ int its_cpu_init(void);
 int its_init(struct fwnode_handle *handle, struct rdists *rdists,
 	     struct irq_domain *domain);
 int mbi_init(struct fwnode_handle *fwnode, struct irq_domain *parent);
+void gic_sgi_set_prio(void __iomem *base, u32 irqnr, u8 prio);
 
 static inline bool gic_enable_sre(void)
 {
-- 
2.17.1