linux-kernel - Re: [PATCH v7 2/8] x86/mce: Unify AMD DFR handler with MCA Polling

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20251024203012.GA251815@yaz-khff2.amd.com>
Date: Fri, 24 Oct 2025 16:30:12 -0400
From: Yazen Ghannam <yazen.ghannam@....com>
To: Borislav Petkov <bp@...en8.de>
Cc: x86@...nel.org, Tony Luck <tony.luck@...el.com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>, linux-kernel@...r.kernel.org,
	linux-edac@...r.kernel.org, Smita.KoralahalliChannabasappa@....com,
	Qiuxu Zhuo <qiuxu.zhuo@...el.com>,
	Nikolay Borisov <nik.borisov@...e.com>,
	Bert Karwatzki <spasswolf@....de>, linux-acpi@...r.kernel.org
Subject: Re: [PATCH v7 2/8] x86/mce: Unify AMD DFR handler with MCA Polling

On Fri, Oct 24, 2025 at 05:03:33PM +0200, Borislav Petkov wrote:
> On Thu, Oct 16, 2025 at 04:37:47PM +0000, Yazen Ghannam wrote:
> > @@ -1878,6 +1924,9 @@ static void __mcheck_cpu_init_prepare_banks(void)
> >  
> >  		bitmap_fill(all_banks, MAX_NR_BANKS);
> >  		machine_check_poll(MCP_UC | MCP_QUEUE_LOG, &all_banks);
> > +
> > +		if (mce_flags.smca)
> > +			machine_check_poll(MCP_DFR | MCP_QUEUE_LOG, &all_banks);
> 
> So you're going to run the poll again just for DFR errors?!
> 
> What for?

Yeah, I guess I went too far with trying to catch bogus errors.

> 
> I think this is enough:
> 
> diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
> index 1482648c8508..7d6588195d56 100644
> --- a/arch/x86/include/asm/mce.h
> +++ b/arch/x86/include/asm/mce.h
> @@ -299,7 +299,6 @@ enum mcp_flags {
>  	MCP_TIMESTAMP	= BIT(0),	/* log time stamp */
>  	MCP_UC		= BIT(1),	/* log uncorrected errors */
>  	MCP_QUEUE_LOG	= BIT(2),	/* only queue to genpool */
> -	MCP_DFR		= BIT(3),	/* log deferred errors */
>  };
>  
>  void machine_check_poll(enum mcp_flags flags, mce_banks_t *b);
> diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
> index 64aa7ecfd332..d9f9ee7db5c8 100644
> --- a/arch/x86/kernel/cpu/mce/amd.c
> +++ b/arch/x86/kernel/cpu/mce/amd.c
> @@ -807,7 +807,7 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_deferred_error)
>  /* APIC interrupt handler for deferred errors */
>  static void amd_deferred_error_interrupt(void)
>  {
> -	machine_check_poll(MCP_TIMESTAMP | MCP_DFR, &this_cpu_ptr(&mce_amd_data)->dfr_intr_banks);
> +	machine_check_poll(MCP_TIMESTAMP, &this_cpu_ptr(&mce_amd_data)->dfr_intr_banks);
>  }
>  
>  static void reset_block(struct threshold_block *block)
> diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
> index 39725df7d35c..7be062429ce3 100644
> --- a/arch/x86/kernel/cpu/mce/core.c
> +++ b/arch/x86/kernel/cpu/mce/core.c
> @@ -779,17 +779,13 @@ static bool should_log_poll_error(enum mcp_flags flags, struct mce_hw_err *err)
>  {
>  	struct mce *m = &err->m;
>  
> -	if (flags & MCP_DFR)
> +	if (mce_flags.smca)
>  		return smca_should_log_poll_error(flags, err);
>  
>  	/* If this entry is not valid, ignore it. */
>  	if (!(m->status & MCI_STATUS_VAL))
>  		return false;
>  
> -	/* Ignore deferred errors if not looking for them (MCP_DFR not set). */
> -	if (m->status & MCI_STATUS_DEFERRED)
> -		return false;
> -
>  	/*
>  	 * If we are logging everything (at CPU online) or this
>  	 * is a corrected error, then we must log it.
> @@ -1924,9 +1920,6 @@ static void __mcheck_cpu_init_prepare_banks(void)
>  
>  		bitmap_fill(all_banks, MAX_NR_BANKS);
>  		machine_check_poll(MCP_UC | MCP_QUEUE_LOG, &all_banks);
> -
> -		if (mce_flags.smca)
> -			machine_check_poll(MCP_DFR | MCP_QUEUE_LOG, &all_banks);
>  	}
>  
>  	for (i = 0; i < this_cpu_read(mce_num_banks); i++) {
> 
> 
> 

This looks good to me.

Should I send another revision?

Thanks,
Yazen