linux-kernel - [PATCH 9/9] x86/mce/amd: Support SMCA Corrected Error Interrupt

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Date: Thu, 23 May 2024 10:56:41 -0500
From: Yazen Ghannam <yazen.ghannam@....com>
To: <linux-edac@...r.kernel.org>
CC: <linux-kernel@...r.kernel.org>, <tony.luck@...el.com>, <x86@...nel.org>,
	<avadhut.naik@....com>, <john.allen@....com>, Yazen Ghannam
	<yazen.ghannam@....com>
Subject: [PATCH 9/9] x86/mce/amd: Support SMCA Corrected Error Interrupt

AMD systems optionally support MCA thresholding which provides the
ability for hardware to send an interrupt when a set error threshold is
reached. This feature counts errors of all severities, but it is
commonly used to report correctable errors with an interrupt rather than
polling.

Scalable MCA systems allow the Platform to take control of this feature.
In this case, the OS will not see the feature configuration and control
bits in the MCA_MISC* registers. The OS will not receive the MCA
thresholding interrupt, and it will need to poll for correctable errors.

A "corrected error interrupt" will be available on Scalable MCA systems.
This will be used in the same configuration where the Platform controls
MCA thresholding. However, the Platform will now be able to send the
MCA thresholding interrupt to the OS.

Check for the feature bit in the MCA_CONFIG register and confirm that
the MCA thresholding interrupt handler is already enabled. If successful,
set the feature enable bit in the MCA_CONFIG register to indicate to the
Platform that the OS is ready for the interrupt.

Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
---
 arch/x86/kernel/cpu/mce/amd.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
index 7acaa21e11e1..cc1527ff76fc 100644
--- a/arch/x86/kernel/cpu/mce/amd.c
+++ b/arch/x86/kernel/cpu/mce/amd.c
@@ -302,6 +302,11 @@ static void smca_configure(unsigned int bank, unsigned int cpu)
 			high |= BIT(5);
 		}

+		if ((low & BIT(10)) && this_cpu_read(smca_thr_intr_enabled)) {
+			__set_bit(bank, this_cpu_ptr(mce_thr_intr_banks));
+			high |= BIT(8);
+		}
+
 		this_cpu_ptr(mce_banks_array)[bank].lsb_in_status = !!(low & BIT(8));

 		wrmsr(smca_config, low, high);
-- 
2.34.1