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Date: Wed, 30 Aug 2023 12:11:22 -0700
From: Douglas Anderson <dianders@...omium.org>
To: Mark Rutland <mark.rutland@....com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Sumit Garg <sumit.garg@...aro.org>,
Daniel Thompson <daniel.thompson@...aro.org>,
Marc Zyngier <maz@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org,
Masayoshi Mizuma <msys.mizuma@...il.com>,
"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
Chen-Yu Tsai <wens@...e.org>,
Lecopzer Chen <lecopzer.chen@...iatek.com>,
Tomohiro Misono <misono.tomohiro@...itsu.com>,
Stephane Eranian <eranian@...gle.com>,
kgdb-bugreport@...ts.sourceforge.net,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Stephen Boyd <swboyd@...omium.org>, ito-yuichi@...itsu.com,
linux-perf-users@...r.kernel.org, Ard Biesheuvel <ardb@...nel.org>,
Douglas Anderson <dianders@...omium.org>,
linux-kernel@...r.kernel.org
Subject: [PATCH v12 1/7] irqchip/gic-v3: Enable support for SGIs to act as NMIs
As of commit 6abbd6988971 ("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@...aro.org>
Signed-off-by: Sumit Garg <sumit.garg@...aro.org>
Signed-off-by: Douglas Anderson <dianders@...omium.org>
---
I'll note that this change is a little more black magic to me than
others in this series. I don't have a massive amounts of familiarity
with all the moving parts of gic-v3, so I mostly just followed Mark
Rutland's advice [1]. Please pay extra attention to make sure I didn't
do anything too terrible.
Mark's advice wasn't a full patch and I ended up doing a bit of work
to translate it to reality, so I did not add him as "Co-developed-by"
here. Mark: if you would like this tag then please provide it and your
Signed-off-by. I certainly won't object.
[1] https://lore.kernel.org/r/ZNC-YRQopO0PaIIo@FVFF77S0Q05N.cambridge.arm.com
Changes in v12:
- Added a comment about why we account for 16 SGIs when Linux uses 8.
Changes in v10:
- Rewrite as needed for 5.11+ as per Mark Rutland and Sumit.
drivers/irqchip/irq-gic-v3.c | 59 +++++++++++++++++++++++++-----------
1 file changed, 41 insertions(+), 18 deletions(-)
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index eedfa8e9f077..8d20122ba0a8 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/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_idx(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_idx(struct irq_data *d)
{
- return __gic_get_ppi_index(d->hwirq);
+ return __gic_get_rdist_idx(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_idx(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_idx(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:
--
2.42.0.283.g2d96d420d3-goog
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