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Message-ID: <20220126095726.GA23794@lpieralisi>
Date: Wed, 26 Jan 2022 09:57:26 +0000
From: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To: Marc Zyngier <maz@...nel.org>
Cc: linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
kernel-team@...roid.com, Jay Chen <jkchen@...ux.alibaba.com>
Subject: Re: [PATCH v3] irqchip/gic-v3-its: Reset each ITS's BASERn register
before probe
On Mon, Jan 24, 2022 at 01:38:09PM +0000, Marc Zyngier wrote:
> A recent bug report outlined that the way GICv4.1 is handled across
> kexec is pretty bad. We can end-up in a situation where ITSs share
> memory (this is the case when SVPET==1) and reprogram the base
> registers, creating a situation where ITSs that are part of a given
> affinity group see different pointers. Which is illegal. Boo.
>
> In order to restore some sanity, reset the BASERn registers to 0
> *before* probing any ITS. Although this isn't optimised at all,
> this is only a once-per-boot cost, which shouldn't show up on
> anyone's radar.
>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Cc: Jay Chen <jkchen@...ux.alibaba.com>
> Signed-off-by: Marc Zyngier <maz@...nel.org>
> Link: https://lore.kernel.org/r/20211216190315.GA14220@lpieralisi
> ---
> drivers/irqchip/irq-gic-v3-its.c | 114 +++++++++++++++++++++++++------
> 1 file changed, 93 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index 7b8f1ec0ff78..c09d99d5b637 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -4856,6 +4856,38 @@ static struct syscore_ops its_syscore_ops = {
> .resume = its_restore_enable,
> };
>
> +static void __init __iomem *its_map_one(struct resource *res, int *err)
> +{
> + void __iomem *its_base;
> + u32 val;
> +
> + its_base = ioremap(res->start, SZ_64K);
> + if (!its_base) {
> + pr_warn("ITS@%pa: Unable to map ITS registers\n", &res->start);
> + *err = -ENOMEM;
> + return NULL;
> + }
> +
> + val = readl_relaxed(its_base + GITS_PIDR2) & GIC_PIDR2_ARCH_MASK;
> + if (val != 0x30 && val != 0x40) {
> + pr_warn("ITS@%pa: No ITS detected, giving up\n", &res->start);
> + *err = -ENODEV;
> + goto out_unmap;
> + }
> +
> + *err = its_force_quiescent(its_base);
> + if (*err) {
> + pr_warn("ITS@%pa: Failed to quiesce, giving up\n", &res->start);
> + goto out_unmap;
> + }
> +
> + return its_base;
> +
> +out_unmap:
> + iounmap(its_base);
> + return NULL;
> +}
> +
> static int its_init_domain(struct fwnode_handle *handle, struct its_node *its)
> {
> struct irq_domain *inner_domain;
> @@ -4963,29 +4995,14 @@ static int __init its_probe_one(struct resource *res,
> {
> struct its_node *its;
> void __iomem *its_base;
> - u32 val, ctlr;
> u64 baser, tmp, typer;
> struct page *page;
> + u32 ctlr;
> int err;
>
> - its_base = ioremap(res->start, SZ_64K);
> - if (!its_base) {
> - pr_warn("ITS@%pa: Unable to map ITS registers\n", &res->start);
> - return -ENOMEM;
> - }
> -
> - val = readl_relaxed(its_base + GITS_PIDR2) & GIC_PIDR2_ARCH_MASK;
> - if (val != 0x30 && val != 0x40) {
> - pr_warn("ITS@%pa: No ITS detected, giving up\n", &res->start);
> - err = -ENODEV;
> - goto out_unmap;
> - }
> -
> - err = its_force_quiescent(its_base);
> - if (err) {
> - pr_warn("ITS@%pa: Failed to quiesce, giving up\n", &res->start);
> - goto out_unmap;
> - }
> + its_base = its_map_one(res, &err);
> + if (!its_base)
> + return err;
>
> pr_info("ITS %pR\n", res);
>
> @@ -5249,6 +5266,23 @@ static int its_cpu_memreserve_lpi(unsigned int cpu)
> return ret;
> }
>
> +/* Mark all the BASER registers as invalid before they get reprogrammed */
> +static int __init its_reset_one(struct resource *res)
> +{
> + void __iomem *its_base;
> + int err, i;
> +
> + its_base = its_map_one(res, &err);
> + if (!its_base)
> + return err;
> +
> + for (i = 0; i < GITS_BASER_NR_REGS; i++)
> + gits_write_baser(0, its_base + GITS_BASER + (i << 3));
> +
> + iounmap(its_base);
> + return 0;
> +}
> +
> static const struct of_device_id its_device_id[] = {
> { .compatible = "arm,gic-v3-its", },
> {},
> @@ -5259,6 +5293,26 @@ static int __init its_of_probe(struct device_node *node)
> struct device_node *np;
> struct resource res;
>
> + /*
> + * Make sure *all* the ITS are reset before we probe any, as
> + * they may be sharing memory. If any of the ITS fails to
> + * reset, don't even try to go any further, as this could
> + * result in something even worse.
> + */
> + for (np = of_find_matching_node(node, its_device_id); np;
> + np = of_find_matching_node(np, its_device_id)) {
> + int err;
> +
> + if (!of_device_is_available(np) ||
> + !of_property_read_bool(np, "msi-controller") ||
> + of_address_to_resource(np, 0, &res))
> + continue;
> +
> + err = its_reset_one(&res);
> + if (err)
> + return err;
> + }
> +
> for (np = of_find_matching_node(node, its_device_id); np;
> np = of_find_matching_node(np, its_device_id)) {
> if (!of_device_is_available(np))
> @@ -5421,11 +5475,29 @@ static int __init gic_acpi_parse_madt_its(union acpi_subtable_headers *header,
> return err;
> }
>
> +static int __init its_acpi_reset(union acpi_subtable_headers *header,
> + const unsigned long end)
> +{
> + struct acpi_madt_generic_translator *its_entry;
> + struct resource res;
> +
> + its_entry = (struct acpi_madt_generic_translator *)header;
> + res = (struct resource) {
> + .start = its_entry->base_address,
> + .end = its_entry->base_address + ACPI_GICV3_ITS_MEM_SIZE - 1,
> + .flags = IORESOURCE_MEM,
> + };
> +
> + return its_reset_one(&res);
> +}
> +
> static void __init its_acpi_probe(void)
> {
> acpi_table_parse_srat_its();
> - acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_TRANSLATOR,
> - gic_acpi_parse_madt_its, 0);
> + if (acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_TRANSLATOR,
> + its_acpi_reset, 0) > 0)
> + acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_TRANSLATOR,
> + gic_acpi_parse_madt_its, 0);
Maybe it is worth adding a comment here as you did for DT if you
can before merging it - to clarify the first acpi_table_parse_madt()
call logic.
Other than that:
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> acpi_its_srat_maps_free();
> }
> #else
> --
> 2.34.1
>
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