irqchip/gic-v3: Enable support for SGIs to act as NMIs

As of commit 6abbd698 ("irqchip/gic, gic-v3: Make SGIs use
handle_percpu_devid_irq()") SGIs are treated the same as PPIs/EPPIs
and use handle_percpu_devid_irq() by default. Unfortunately,
handle_percpu_devid_irq() isn't NMI safe, and so to run in an NMI
context those should use handle_percpu_devid_fasteoi_nmi().

In order to accomplish this, we just have to make room for SGIs in the
array of refcounts that keeps track of which interrupts are set as
NMI. We also rename the array and create a new indexing scheme that
accounts for SGIs.

Also, enable NMI support prior to gic_smp_init() as allocation of SGIs
as IRQs/NMIs happen as part of this routine.
Co-developed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230906090246.v13.1.I1223c11c88937bd0cbd9b086d4ef216985797302@changeidSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

drivers/irqchip/irq-gic-v3.c

@@ -78,6 +78,13 @@ static DEFINE_STATIC_KEY_TRUE(supports_deactivate_key);
 #define GIC_LINE_NR	min(GICD_TYPER_SPIS(gic_data.rdists.gicd_typer), 1020U)
 #define GIC_ESPI_NR	GICD_TYPER_ESPIS(gic_data.rdists.gicd_typer)
 
+/*
+ * There are 16 SGIs, though we only actually use 8 in Linux. The other 8 SGIs
+ * are potentially stolen by the secure side. Some code, especially code dealing
+ * with hwirq IDs, is simplified by accounting for all 16.
+ */
+#define SGI_NR		16
+
 /*
  * The behaviours of RPR and PMR registers differ depending on the value of
  * SCR_EL3.FIQ, and the behaviour of non-secure priority registers of the
@@ -125,8 +132,8 @@ EXPORT_SYMBOL(gic_nonsecure_priorities);
 		__priority;						\
 	})
 
-/* ppi_nmi_refs[n] == number of cpus having ppi[n + 16] set as NMI */
-static refcount_t *ppi_nmi_refs;
+/* rdist_nmi_refs[n] == number of cpus having the rdist interrupt n set as NMI */
+static refcount_t *rdist_nmi_refs;
 
 static struct gic_kvm_info gic_v3_kvm_info __initdata;
 static DEFINE_PER_CPU(bool, has_rss);
@@ -519,9 +526,22 @@ static u32 __gic_get_ppi_index(irq_hw_number_t hwirq)
 	}
 }
 
-static u32 gic_get_ppi_index(struct irq_data *d)
+static u32 __gic_get_rdist_index(irq_hw_number_t hwirq)
+{
+	switch (__get_intid_range(hwirq)) {
+	case SGI_RANGE:
+	case PPI_RANGE:
+		return hwirq;
+	case EPPI_RANGE:
+		return hwirq - EPPI_BASE_INTID + 32;
+	default:
+		unreachable();
+	}
+}
+
+static u32 gic_get_rdist_index(struct irq_data *d)
 {
-	return __gic_get_ppi_index(d->hwirq);
+	return __gic_get_rdist_index(d->hwirq);
 }
 
 static int gic_irq_nmi_setup(struct irq_data *d)
@@ -545,11 +565,14 @@ static int gic_irq_nmi_setup(struct irq_data *d)
 
 	/* desc lock should already be held */
 	if (gic_irq_in_rdist(d)) {
-		u32 idx = gic_get_ppi_index(d);
+		u32 idx = gic_get_rdist_index(d);
 
-		/* Setting up PPI as NMI, only switch handler for first NMI */
-		if (!refcount_inc_not_zero(&ppi_nmi_refs[idx])) {
-			refcount_set(&ppi_nmi_refs[idx], 1);
+		/*
+		 * Setting up a percpu interrupt as NMI, only switch handler
+		 * for first NMI
+		 */
+		if (!refcount_inc_not_zero(&rdist_nmi_refs[idx])) {
+			refcount_set(&rdist_nmi_refs[idx], 1);
 			desc->handle_irq = handle_percpu_devid_fasteoi_nmi;
 		}
 	} else {
@@ -582,10 +605,10 @@ static void gic_irq_nmi_teardown(struct irq_data *d)
 
 	/* desc lock should already be held */
 	if (gic_irq_in_rdist(d)) {
-		u32 idx = gic_get_ppi_index(d);
+		u32 idx = gic_get_rdist_index(d);
 
 		/* Tearing down NMI, only switch handler for last NMI */
-		if (refcount_dec_and_test(&ppi_nmi_refs[idx]))
+		if (refcount_dec_and_test(&rdist_nmi_refs[idx]))
 			desc->handle_irq = handle_percpu_devid_irq;
 	} else {
 		desc->handle_irq = handle_fasteoi_irq;
@@ -1279,10 +1302,10 @@ static void gic_cpu_init(void)
 	rbase = gic_data_rdist_sgi_base();
 
 	/* Configure SGIs/PPIs as non-secure Group-1 */
-	for (i = 0; i < gic_data.ppi_nr + 16; i += 32)
+	for (i = 0; i < gic_data.ppi_nr + SGI_NR; i += 32)
 		writel_relaxed(~0, rbase + GICR_IGROUPR0 + i / 8);
 
-	gic_cpu_config(rbase, gic_data.ppi_nr + 16, gic_redist_wait_for_rwp);
+	gic_cpu_config(rbase, gic_data.ppi_nr + SGI_NR, gic_redist_wait_for_rwp);
 
 	/* initialise system registers */
 	gic_cpu_sys_reg_init();
@@ -1939,12 +1962,13 @@ static void gic_enable_nmi_support(void)
 		return;
 	}
 
-	ppi_nmi_refs = kcalloc(gic_data.ppi_nr, sizeof(*ppi_nmi_refs), GFP_KERNEL);
-	if (!ppi_nmi_refs)
+	rdist_nmi_refs = kcalloc(gic_data.ppi_nr + SGI_NR,
+				 sizeof(*rdist_nmi_refs), GFP_KERNEL);
+	if (!rdist_nmi_refs)
 		return;
 
-	for (i = 0; i < gic_data.ppi_nr; i++)
-		refcount_set(&ppi_nmi_refs[i], 0);
+	for (i = 0; i < gic_data.ppi_nr + SGI_NR; i++)
+		refcount_set(&rdist_nmi_refs[i], 0);
 
 	pr_info("Pseudo-NMIs enabled using %s ICC_PMR_EL1 synchronisation\n",
 		gic_has_relaxed_pmr_sync() ? "relaxed" : "forced");
@@ -2061,6 +2085,7 @@ static int __init gic_init_bases(phys_addr_t dist_phys_base,
 
 	gic_dist_init();
 	gic_cpu_init();
+	gic_enable_nmi_support();
 	gic_smp_init();
 	gic_cpu_pm_init();
 
@@ -2073,8 +2098,6 @@ static int __init gic_init_bases(phys_addr_t dist_phys_base,
 			gicv2m_init(handle, gic_data.domain);
 	}
 
-	gic_enable_nmi_support();
-
 	return 0;
 
 out_free: