88 lines
3.2 KiB
Diff
88 lines
3.2 KiB
Diff
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From c6f62870f27ece45e944d1818f6aa04b3e024959 Mon Sep 17 00:00:00 2001
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From: Thomas Huth <thuth@redhat.com>
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Date: Thu, 10 Dec 2020 08:32:41 -0500
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Subject: [PATCH 5/5] pc-bios: s390x: Clear out leftover S390EP string
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RH-Author: Thomas Huth <thuth@redhat.com>
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Message-id: <20201210083241.173509-5-thuth@redhat.com>
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Patchwork-id: 100369
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O-Subject: [RHEL-8.4.0 qemu-kvm PATCH 4/4] pc-bios: s390x: Clear out leftover S390EP string
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Bugzilla: 1903135
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RH-Acked-by: Cornelia Huck <cohuck@redhat.com>
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RH-Acked-by: Jens Freimann <jfreimann@redhat.com>
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RH-Acked-by: David Hildenbrand <david@redhat.com>
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From: Eric Farman <farman@linux.ibm.com>
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A Linux binary will have the string "S390EP" at address 0x10008,
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which is important in getting the guest up off the ground. In the
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case of a reboot (specifically chreipl going to a new device),
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we should defer to the PSW at address zero for the new config,
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which will re-write "S390EP" from the new image.
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Let's clear it out at this point so that a reipl to, say, a DASD
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passthrough device drives the IPL path from scratch without disrupting
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disrupting the order of operations for other boots.
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Rather than hardcoding the address of this magic (again), let's
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define it somewhere so that the two users are visibly related.
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Signed-off-by: Eric Farman <farman@linux.ibm.com>
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Message-Id: <20201120160117.59366-3-farman@linux.ibm.com>
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Signed-off-by: Thomas Huth <thuth@redhat.com>
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(cherry picked from commit 3d6519968bb10260fc724c491fb4275f7c0b78ac)
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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pc-bios/s390-ccw/jump2ipl.c | 2 +-
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pc-bios/s390-ccw/main.c | 6 ++++++
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pc-bios/s390-ccw/s390-arch.h | 3 +++
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3 files changed, 10 insertions(+), 1 deletion(-)
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diff --git a/pc-bios/s390-ccw/jump2ipl.c b/pc-bios/s390-ccw/jump2ipl.c
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index 767012bf0c9..6c6823b5db8 100644
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--- a/pc-bios/s390-ccw/jump2ipl.c
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+++ b/pc-bios/s390-ccw/jump2ipl.c
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@@ -78,7 +78,7 @@ void jump_to_low_kernel(void)
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* kernel start address (when jumping to the PSW-at-zero address instead,
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* the kernel startup code fails when we booted from a network device).
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*/
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- if (!memcmp((char *)0x10008, "S390EP", 6)) {
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+ if (!memcmp((char *)S390EP, "S390EP", 6)) {
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jump_to_IPL_code(KERN_IMAGE_START);
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}
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diff --git a/pc-bios/s390-ccw/main.c b/pc-bios/s390-ccw/main.c
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index e3a1a3053d0..c04b910082b 100644
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--- a/pc-bios/s390-ccw/main.c
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+++ b/pc-bios/s390-ccw/main.c
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@@ -185,6 +185,12 @@ static void boot_setup(void)
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memcpy(lpmsg + 10, loadparm_str, 8);
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sclp_print(lpmsg);
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+ /*
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+ * Clear out any potential S390EP magic (see jump_to_low_kernel()),
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+ * so we don't taint our decision-making process during a reboot.
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+ */
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+ memset((char *)S390EP, 0, 6);
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+
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have_iplb = store_iplb(&iplb);
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}
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diff --git a/pc-bios/s390-ccw/s390-arch.h b/pc-bios/s390-ccw/s390-arch.h
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index 6da44d4436c..a741488aaa1 100644
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--- a/pc-bios/s390-ccw/s390-arch.h
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+++ b/pc-bios/s390-ccw/s390-arch.h
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@@ -95,6 +95,9 @@ typedef struct LowCore {
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extern LowCore *lowcore;
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+/* Location of "S390EP" in a Linux binary (see arch/s390/boot/head.S) */
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+#define S390EP 0x10008
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+
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static inline void set_prefix(uint32_t address)
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{
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asm volatile("spx %0" : : "m" (address) : "memory");
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--
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2.27.0
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