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

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Message-ID: <20251024150333.GSaPuVRQYxH92zyrmO@fat_crate.local>
Date: Fri, 24 Oct 2025 17:03:33 +0200
From: Borislav Petkov <bp@...en8.de>
To: Yazen Ghannam <yazen.ghannam@....com>
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 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?

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++) {



-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette