irqchip/gic-v3-its: Reset each ITS's BASERn register before probe

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: Jay Chen <jkchen@linux.alibaba.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Link: https://lore.kernel.org/r/20211216190315.GA14220@lpieralisi
Link: https://lore.kernel.org/r/20220124133809.1291195-1-maz@kernel.org

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 7b8f1ec..220fa45 100644 (file)
--- 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 @@ out:
        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 +5475,35 @@ dom_err:
        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);
+       /*
+        * 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.
+        */
+       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);
        acpi_its_srat_maps_free();
 }
 #else