From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Fri, 9 Jan 2026 10:48:34 +0000 (+0100)
Subject: Revert "iommu/amd: Skip enabling command/event buffers for kdump"
X-Git-Tag: v5.10.248~47
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=816b2eac151a9bcce4eff7119207e088ad45236f;p=thirdparty%2Fkernel%2Fstable.git

Revert "iommu/amd: Skip enabling command/event buffers for kdump"

This reverts commit 30e91eeb0bc9b3daf402b26176d1d52c29ab53e4 which is
commit 9be15fbfc6c5c89c22cf6e209f66ea43ee0e58bb upstream.

This causes problems in older kernel trees as SNP host kdump is not
supported in them, so drop it from the stable branches.

Reported-by: Ashish Kalra <ashish.kalra@amd.com>
Link: https://lore.kernel.org/r/dacdff7f-0606-4ed5-b056-2de564404d51@amd.com
Cc: Vasant Hegde <vasant.hegde@amd.com>
Cc: Sairaj Kodilkar <sarunkod@amd.com>
Cc: Joerg Roedel <joerg.roedel@amd.com>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 8ac0ac915efd3..1ba6adb5b9124 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -697,16 +697,11 @@ static void iommu_enable_command_buffer(struct amd_iommu *iommu)
 
 	BUG_ON(iommu->cmd_buf == NULL);
 
-	if (!is_kdump_kernel()) {
-		/*
-		 * Command buffer is re-used for kdump kernel and setting
-		 * of MMIO register is not required.
-		 */
-		entry = iommu_virt_to_phys(iommu->cmd_buf);
-		entry |= MMIO_CMD_SIZE_512;
-		memcpy_toio(iommu->mmio_base + MMIO_CMD_BUF_OFFSET,
-			    &entry, sizeof(entry));
-	}
+	entry = iommu_virt_to_phys(iommu->cmd_buf);
+	entry |= MMIO_CMD_SIZE_512;
+
+	memcpy_toio(iommu->mmio_base + MMIO_CMD_BUF_OFFSET,
+		    &entry, sizeof(entry));
 
 	amd_iommu_reset_cmd_buffer(iommu);
 }
@@ -755,15 +750,10 @@ static void iommu_enable_event_buffer(struct amd_iommu *iommu)
 
 	BUG_ON(iommu->evt_buf == NULL);
 
-	if (!is_kdump_kernel()) {
-		/*
-		 * Event buffer is re-used for kdump kernel and setting
-		 * of MMIO register is not required.
-		 */
-		entry = iommu_virt_to_phys(iommu->evt_buf) | EVT_LEN_MASK;
-		memcpy_toio(iommu->mmio_base + MMIO_EVT_BUF_OFFSET,
-			    &entry, sizeof(entry));
-	}
+	entry = iommu_virt_to_phys(iommu->evt_buf) | EVT_LEN_MASK;
+
+	memcpy_toio(iommu->mmio_base + MMIO_EVT_BUF_OFFSET,
+		    &entry, sizeof(entry));
 
 	/* set head and tail to zero manually */
 	writel(0x00, iommu->mmio_base + MMIO_EVT_HEAD_OFFSET);