The definition of the GICR_CTLR.RWP control bit was expanded to indicate status of changing GICR_CTLR.EnableLPI from 1 to 0 is being in progress or completed. Software must observe GICR_CTLR.RWP==0 after clearing GICR_CTLR.EnableLPI from 1 to 0 and before writing GICR_PENDBASER and/or GICR_PROPBASER, otherwise behavior is UNPREDICTABLE.
Signed-off-by: Shanker Donthineni <shank...@codeaurora.org> --- Changes since v2: -Revert readl_relaxed_poll() usage since it's not usable in GICv3 probe(). -Changes to pr_xxx messages. Changes since v1: -Moved LPI disable code to a seperate function as Marc suggested. -Mark's suggestion to use readl_relaxed_poll_timeout() helper functions. drivers/irqchip/irq-gic-v3-its.c | 75 +++++++++++++++++++++++++++++++------- include/linux/irqchip/arm-gic-v3.h | 1 + 2 files changed, 62 insertions(+), 14 deletions(-) diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index 2cbb19c..c1e8a8e 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -33,6 +33,7 @@ #include <linux/of_platform.h> #include <linux/percpu.h> #include <linux/slab.h> +#include <linux/time64.h> #include <linux/irqchip.h> #include <linux/irqchip/arm-gic-v3.h> @@ -1875,16 +1876,6 @@ 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 | @@ -3287,13 +3278,69 @@ 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. + * Bail out the driver probe() in case of timeout. + */ + while (readl_relaxed(rbase + GICR_CTLR) & GICR_CTLR_RWP) { + if (!timeout) { + pr_err("CPU%d: Failed to observe RWP==0 after disabling LPIs\n", + smp_processor_id()); + return -ETIMEDOUT; + } + udelay(1); + timeout--; + } + + /** + * After it has been written to 1, it is IMPLEMENTATION DEFINED whether + * the bit GICR_CTLR.EnableLPI becomes RES1 or can be cleared to 0. + * Bail out the driver probe() on systems where it's RES1. + */ + 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_collection(); } diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h index b26eccc..c6f4c48 100644 --- a/include/linux/irqchip/arm-gic-v3.h +++ b/include/linux/irqchip/arm-gic-v3.h @@ -106,6 +106,7 @@ #define GICR_PIDR2 GICD_PIDR2 #define GICR_CTLR_ENABLE_LPIS (1UL << 0) +#define GICR_CTLR_RWP (1UL << 3) #define GICR_TYPER_CPU_NUMBER(r) (((r) >> 8) & 0xffff) -- Qualcomm Datacenter Technologies, Inc. on behalf of the Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.