From b00d41629d81f2f2da92cbbc6f89f844613d7621 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Fri, 9 Jan 2026 11:48:34 +0100 Subject: [PATCH] Revert "iommu/amd: Skip enabling command/event buffers for kdump" This reverts commit 3344716ddee01d7caa35b470d30fd87781c661b1 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 Link: https://lore.kernel.org/r/dacdff7f-0606-4ed5-b056-2de564404d51@amd.com Cc: Vasant Hegde Cc: Sairaj Kodilkar Cc: Joerg Roedel Cc: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/iommu/amd/init.c | 28 +++++++++------------------- 1 file changed, 9 insertions(+), 19 deletions(-) diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c index 8659cb0bc7e6..e1816ae8699d 100644 --- a/drivers/iommu/amd/init.c +++ b/drivers/iommu/amd/init.c @@ -816,16 +816,11 @@ 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); } @@ -874,15 +869,10 @@ 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);