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authorShanker Donthineni <shankerd@codeaurora.org>2018-03-22 04:58:49 +0300
committerMarc Zyngier <marc.zyngier@arm.com>2018-03-23 12:24:25 +0300
commit6eb486b66a3094cdcd68dc39c9df3a29d6a51dd5 (patch)
tree95e04c50da1d0477c2ce6a23ebe63ea4c4c8b139 /drivers/irqchip
parent19d99164480a34db66941cf995bdd996cc266fc0 (diff)
downloadlinux-6eb486b66a3094cdcd68dc39c9df3a29d6a51dd5.tar.xz
irqchip/gic-v3: Ensure GICR_CTLR.EnableLPI=0 is observed before enabling
Booting with GICR_CTLR.EnableLPI=1 is usually a bad idea, and may result in subtle memory corruption. Detecting this is thus pretty important. On detecting that LPIs are still enabled, we taint the kernel (because we're not sure of anything anymore), and try to disable LPIs. This can fail, as implementations are allowed to implement GICR_CTLR.EnableLPI as a one-way enable, meaning the redistributors cannot be reprogrammed with new tables. Should this happen, we fail probing the redistributor and warn the user that things are pretty dire. Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org> [maz: reworded changelog, minor comment and message changes] Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Diffstat (limited to 'drivers/irqchip')
-rw-r--r--drivers/irqchip/irq-gic-v3-its.c74
1 files changed, 60 insertions, 14 deletions
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 2c9006726450..cb952c073d77 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1879,16 +1879,6 @@ static void its_cpu_init_lpis(void)
gic_data_rdist()->pend_page = pend_page;
}
- /* Disable LPIs */
- val = readl_relaxed(rbase + GICR_CTLR);
- val &= ~GICR_CTLR_ENABLE_LPIS;
- writel_relaxed(val, rbase + GICR_CTLR);
-
- /*
- * Make sure any change to the table is observable by the GIC.
- */
- dsb(sy);
-
/* set PROPBASE */
val = (page_to_phys(gic_rdists->prop_page) |
GICR_PROPBASER_InnerShareable |
@@ -3403,13 +3393,69 @@ static bool gic_rdists_supports_plpis(void)
return !!(gic_read_typer(gic_data_rdist_rd_base() + GICR_TYPER) & GICR_TYPER_PLPIS);
}
+static int redist_disable_lpis(void)
+{
+ void __iomem *rbase = gic_data_rdist_rd_base();
+ u64 timeout = USEC_PER_SEC;
+ u64 val;
+
+ if (!gic_rdists_supports_plpis()) {
+ pr_info("CPU%d: LPIs not supported\n", smp_processor_id());
+ return -ENXIO;
+ }
+
+ val = readl_relaxed(rbase + GICR_CTLR);
+ if (!(val & GICR_CTLR_ENABLE_LPIS))
+ return 0;
+
+ pr_warn("CPU%d: Booted with LPIs enabled, memory probably corrupted\n",
+ smp_processor_id());
+ add_taint(TAINT_CRAP, LOCKDEP_STILL_OK);
+
+ /* Disable LPIs */
+ val &= ~GICR_CTLR_ENABLE_LPIS;
+ writel_relaxed(val, rbase + GICR_CTLR);
+
+ /* Make sure any change to GICR_CTLR is observable by the GIC */
+ dsb(sy);
+
+ /*
+ * Software must observe RWP==0 after clearing GICR_CTLR.EnableLPIs
+ * from 1 to 0 before programming GICR_PEND{PROP}BASER registers.
+ * Error out if we time out waiting for RWP to clear.
+ */
+ while (readl_relaxed(rbase + GICR_CTLR) & GICR_CTLR_RWP) {
+ if (!timeout) {
+ pr_err("CPU%d: Timeout while disabling LPIs\n",
+ smp_processor_id());
+ return -ETIMEDOUT;
+ }
+ udelay(1);
+ timeout--;
+ }
+
+ /*
+ * After it has been written to 1, it is IMPLEMENTATION
+ * DEFINED whether GICR_CTLR.EnableLPI becomes RES1 or can be
+ * cleared to 0. Error out if clearing the bit failed.
+ */
+ if (readl_relaxed(rbase + GICR_CTLR) & GICR_CTLR_ENABLE_LPIS) {
+ pr_err("CPU%d: Failed to disable LPIs\n", smp_processor_id());
+ return -EBUSY;
+ }
+
+ return 0;
+}
+
int its_cpu_init(void)
{
if (!list_empty(&its_nodes)) {
- if (!gic_rdists_supports_plpis()) {
- pr_info("CPU%d: LPIs not supported\n", smp_processor_id());
- return -ENXIO;
- }
+ int ret;
+
+ ret = redist_disable_lpis();
+ if (ret)
+ return ret;
+
its_cpu_init_lpis();
its_cpu_init_collections();
}