irqchip/gic-v3-its: Use pre-programmed redistributor tables with kdump kernels

mainline inclusion
from 4.20-rc1
commit: c6e2ccb66d0c3b4fffc59932585e9f709ad59003
category: kdump
bugzilla: 5272
CVE: NA

This 10 patches is used for secondary kernel using LPI.

[PATCH 01/10] irqchip/gic-v3-its: Change initialization ordering for LPIs
[PATCH 02/10] irqchip/gic-v3-its: Simplify LPI_PENDBASE_SZ usage
[PATCH 03/10] irqchip/gic-v3-its: Split property table clearing from allocation
[PATCH 04/10] irqchip/gic-v3-its: Move pending table allocation to init time
[PATCH 05/10] irqchip/gic-v3-its: Keep track of property table's PA and VA
[PATCH 06/10] irqchip/gic-v3-its: Allow use of pre-programmed LPI tables
[PATCH 07/10] irqchip/gic-v3-its: Use pre-programmed redistributor tables with kdump kernels
[PATCH 08/10] irqchip/gic-v3-its: Check that all RDs have the same property table
[PATCH 09/10] irqchip/gic-v3-its: Register LPI tables with EFI config table
[PATCH 10/10] irqchip/gic-v3-its: Allow use of LPI tables in reserved memory

--------------------------------------

If using a kdump kernel, and that we cannot disable LPIs to install
our own tables, let's switch to using the already allocated tables.

This means that we'll change some of the initial kernel's memory,
but at least we'll be able to have LPIs in this secondary kernel.
Tested-by: NJeremy Linton <jeremy.linton@arm.com>
Tested-by: NBhupesh Sharma <bhsharma@redhat.com>
Tested-by: NLei Zhang <zhang.lei@jp.fujitsu.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NHanjun Guo <guohanjun@huawei.com>

drivers/irqchip/irq-gic-v3-its.c

@@ -19,6 +19,7 @@
 #include <linux/acpi_iort.h>
 #include <linux/bitmap.h>
 #include <linux/cpu.h>
+#include <linux/crash_dump.h>
 #include <linux/delay.h>
 #include <linux/dma-iommu.h>
 #include <linux/interrupt.h>
@@ -1963,8 +1964,15 @@ static void its_free_pending_table(struct page *pt)
 	free_pages((unsigned long)page_address(pt), get_order(LPI_PENDBASE_SZ));
 }
 
+/*
+ * Booting with kdump and LPIs enabled is generally fine.
+ */
 static bool enabled_lpis_allowed(void)
 {
+	/* Allow a kdump kernel */
+	if (is_kdump_kernel())
+		return true;
+
 	return false;
 }