linux-kernel - Re: [PATCH v2 linux-next 1/3] x86, crash: don't nest CONFIG_CRASH_DUMP ifdef inside CONFIG_KEXEC

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Date: Tue, 30 Jan 2024 10:59:59 +0800
From: Baoquan He <bhe@...hat.com>
To: kexec@...ts.infradead.org, akpm@...ux-foundation.org
Cc: linux-kernel@...r.kernel.org, x86@...nel.org,
	linux-arm-kernel@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org,
	linux-s390@...r.kernel.org, nathan@...nel.org, mhklinux@...look.com
Subject: Re: [PATCH v2 linux-next 1/3] x86, crash: don't nest
 CONFIG_CRASH_DUMP ifdef inside CONFIG_KEXEC_CODE ifdef scope

Michael pointed out that the CONFIG_CRASH_DUMP ifdef is nested inside
CONFIG_KEXEC_CODE ifdef scope in some XEN, Hyper-V codes.

Although the nesting works well too since CONFIG_CRASH_DUMP has
dependency on CONFIG_KEXEC_CORE, it may cause confusion because there
are places where it's not nested, and people may think it needs to be
nested even though it doesn't have to.

Fix that by moving  CONFIG_CRASH_DUMP ifdeffery of codes out of
CONFIG_KEXEC_CODE ifdeffery scope.

And also put function machine_crash_shutdown() definition inside
CONFIG_CRASH_DUMP ifdef scope instead of CONFIG_KEXEC_CORE ifdef.

And also fix a building error Nathan reported as below by replacing
CONFIG_KEXEC_CORE ifdef with CONFIG_VMCORE_INFO ifdef.

====
$ curl -LSso .config https://git.alpinelinux.org/aports/plain/community/linux-edge/config-edge.x86_64
$ make -skj"$(nproc)" ARCH=x86_64 CROSS_COMPILE=x86_64-linux- olddefconfig all
..
x86_64-linux-ld: arch/x86/xen/mmu_pv.o: in function `paddr_vmcoreinfo_note':
mmu_pv.c:(.text+0x3af3): undefined reference to `vmcoreinfo_note'
====

Link: https://lore.kernel.org/all/SN6PR02MB4157931105FA68D72E3D3DB8D47B2@SN6PR02MB4157.namprd02.prod.outlook.com/T/#u
Link: https://lore.kernel.org/all/20240126045551.GA126645@dev-arch.thelio-3990X/T/#u
Signed-off-by: Baoquan He <bhe@...hat.com>
---
v1->v2:
- Add missing words and fix typos in patch log pointed out by Michael.

 arch/x86/kernel/cpu/mshyperv.c | 10 ++++++----
 arch/x86/kernel/reboot.c       |  2 +-
 arch/x86/xen/enlighten_hvm.c   |  4 ++--
 arch/x86/xen/mmu_pv.c          |  2 +-
 4 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index f8163a59026b..2e8cd5a4ae85 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -209,6 +209,7 @@ static void hv_machine_shutdown(void)
 	if (kexec_in_progress)
 		hyperv_cleanup();
 }
+#endif /* CONFIG_KEXEC_CORE */
 
 #ifdef CONFIG_CRASH_DUMP
 static void hv_machine_crash_shutdown(struct pt_regs *regs)
@@ -222,8 +223,7 @@ static void hv_machine_crash_shutdown(struct pt_regs *regs)
 	/* Disable the hypercall page when there is only 1 active CPU. */
 	hyperv_cleanup();
 }
-#endif
-#endif /* CONFIG_KEXEC_CORE */
+#endif /* CONFIG_CRASH_DUMP */
 #endif /* CONFIG_HYPERV */
 
 static uint32_t  __init ms_hyperv_platform(void)
@@ -497,9 +497,11 @@ static void __init ms_hyperv_init_platform(void)
 	no_timer_check = 1;
 #endif
 
-#if IS_ENABLED(CONFIG_HYPERV) && defined(CONFIG_KEXEC_CORE)
+#if IS_ENABLED(CONFIG_HYPERV)
+#if defined(CONFIG_KEXEC_CORE)
 	machine_ops.shutdown = hv_machine_shutdown;
-#ifdef CONFIG_CRASH_DUMP
+#endif
+#if defined(CONFIG_CRASH_DUMP)
 	machine_ops.crash_shutdown = hv_machine_crash_shutdown;
 #endif
 #endif
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 1287b0d5962f..f3130f762784 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -826,7 +826,7 @@ void machine_halt(void)
 	machine_ops.halt();
 }
 
-#ifdef CONFIG_KEXEC_CORE
+#ifdef CONFIG_CRASH_DUMP
 void machine_crash_shutdown(struct pt_regs *regs)
 {
 	machine_ops.crash_shutdown(regs);
diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
index 09e3db7ff990..0b367c1e086d 100644
--- a/arch/x86/xen/enlighten_hvm.c
+++ b/arch/x86/xen/enlighten_hvm.c
@@ -148,6 +148,7 @@ static void xen_hvm_shutdown(void)
 	if (kexec_in_progress)
 		xen_reboot(SHUTDOWN_soft_reset);
 }
+#endif
 
 #ifdef CONFIG_CRASH_DUMP
 static void xen_hvm_crash_shutdown(struct pt_regs *regs)
@@ -156,7 +157,6 @@ static void xen_hvm_crash_shutdown(struct pt_regs *regs)
 	xen_reboot(SHUTDOWN_soft_reset);
 }
 #endif
-#endif
 
 static int xen_cpu_up_prepare_hvm(unsigned int cpu)
 {
@@ -238,10 +238,10 @@ static void __init xen_hvm_guest_init(void)
 
 #ifdef CONFIG_KEXEC_CORE
 	machine_ops.shutdown = xen_hvm_shutdown;
+#endif
 #ifdef CONFIG_CRASH_DUMP
 	machine_ops.crash_shutdown = xen_hvm_crash_shutdown;
 #endif
-#endif
 }
 
 static __init int xen_parse_nopv(char *arg)
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index 218773cfb009..e21974f2cf2d 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -2520,7 +2520,7 @@ int xen_remap_pfn(struct vm_area_struct *vma, unsigned long addr,
 }
 EXPORT_SYMBOL_GPL(xen_remap_pfn);
 
-#ifdef CONFIG_KEXEC_CORE
+#ifdef CONFIG_VMCORE_INFO
 phys_addr_t paddr_vmcoreinfo_note(void)
 {
 	if (xen_pv_domain())
-- 
2.41.0