linux-kernel - Re: [PATCH v3 2/2] powerpc/fadump: make is_kdump_kernel() return false when fadump is active

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Message-ID: <ZQKPEd09+XvnQ5RN@MiWiFi-R3L-srv>
Date:   Thu, 14 Sep 2023 12:41:53 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Hari Bathini <hbathini@...ux.ibm.com>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Kexec-ml <kexec@...ts.infradead.org>,
        Dave Young <dyoung@...hat.com>,
        Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
        Sourabh Jain <sourabhjain@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: Re: [PATCH v3 2/2] powerpc/fadump: make is_kdump_kernel() return
 false when fadump is active

On 09/12/23 at 01:59pm, Hari Bathini wrote:
> Currently, is_kdump_kernel() returns true in crash dump capture kernel
> for both kdump and fadump crash dump capturing methods, as both these
> methods set elfcorehdr_addr. Some restrictions enforced for crash dump
> capture kernel, based on is_kdump_kernel(), are specifically meant for
> kdump case and not desirable for fadump - eg. IO queues restriction in
> device drivers. So, define is_kdump_kernel() to return false when f/w
> assisted dump is active.
> 
> Signed-off-by: Hari Bathini <hbathini@...ux.ibm.com>
> ---
>  arch/powerpc/include/asm/kexec.h |  8 ++++++--
>  arch/powerpc/kernel/crash_dump.c | 12 ++++++++++++
>  2 files changed, 18 insertions(+), 2 deletions(-)

LGTM,

Acked-by: Baoquan He <bhe@...hat.com>

> 
> diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
> index a1ddba01e7d1..e1b43aa12175 100644
> --- a/arch/powerpc/include/asm/kexec.h
> +++ b/arch/powerpc/include/asm/kexec.h
> @@ -99,10 +99,14 @@ void relocate_new_kernel(unsigned long indirection_page, unsigned long reboot_co
>  
>  void kexec_copy_flush(struct kimage *image);
>  
> -#if defined(CONFIG_CRASH_DUMP) && defined(CONFIG_PPC_RTAS)
> +#if defined(CONFIG_CRASH_DUMP)
> +bool is_kdump_kernel(void);
> +#define is_kdump_kernel			is_kdump_kernel
> +#if defined(CONFIG_PPC_RTAS)
>  void crash_free_reserved_phys_range(unsigned long begin, unsigned long end);
>  #define crash_free_reserved_phys_range crash_free_reserved_phys_range
> -#endif
> +#endif /* CONFIG_PPC_RTAS */
> +#endif /* CONFIG_CRASH_DUMP */
>  
>  #ifdef CONFIG_KEXEC_FILE
>  extern const struct kexec_file_ops kexec_elf64_ops;
> diff --git a/arch/powerpc/kernel/crash_dump.c b/arch/powerpc/kernel/crash_dump.c
> index 9a3b85bfc83f..2086fa6cdc25 100644
> --- a/arch/powerpc/kernel/crash_dump.c
> +++ b/arch/powerpc/kernel/crash_dump.c
> @@ -19,6 +19,7 @@
>  #include <linux/uio.h>
>  #include <asm/rtas.h>
>  #include <asm/inst.h>
> +#include <asm/fadump.h>
>  
>  #ifdef DEBUG
>  #include <asm/udbg.h>
> @@ -92,6 +93,17 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
>  	return csize;
>  }
>  
> +/*
> + * Return true only when kexec based kernel dump capturing method is used.
> + * This ensures all restritions applied for kdump case are not automatically
> + * applied for fadump case.
> + */
> +bool is_kdump_kernel(void)
> +{
> +	return !is_fadump_active() && elfcorehdr_addr != ELFCORE_ADDR_MAX;
> +}
> +EXPORT_SYMBOL_GPL(is_kdump_kernel);
> +
>  #ifdef CONFIG_PPC_RTAS
>  /*
>   * The crashkernel region will almost always overlap the RTAS region, so
> -- 
> 2.41.0
>