Re: [PATCH V1] iommu/hyperv: Create hyperv subdirectory under drivers/iommu

[Jacob Pan <jacob.pan@linux.microsoft.com>]

Hi Mukesh,

On Thu, 28 May 2026 18:41:48 -0700
Mukesh R <mrathor@linux.microsoft.com> wrote:

> Create hyperv subdirectory under drivers/iommu in anticipation of more
> hyperv related files from upcoming PCI passthru and pv-IOMMU patches.
> Also, the current file hyperv-iommu.c actually implements irq
> remapping, so rename to more appropriate hv-irq-remap.c and move it
> under the new hyperv subdirectory. Since this file implements
> irq_remap_ops exposed by drivers/iommu/irq_remapping.h, it cannot be
> relocated to the irq directory. This is in sync with other backend
> directories like amd and intel there.
> 
> Lastly, this file should not be tied to CONFIG_HYPERV_IOMMU, but to
> CONFIG_HYPERV and CONFIG_IRQ_REMAP.
> 
> Signed-off-by: Mukesh R <mrathor@linux.microsoft.com>
> ---
>  MAINTAINERS                                             | 2 +-
>  drivers/iommu/Kconfig                                   | 9 ---------
>  drivers/iommu/Makefile                                  | 2 +-
>  drivers/iommu/hyperv/Makefile                           | 2 ++
>  drivers/iommu/{hyperv-iommu.c => hyperv/hv-irq-remap.c} | 8 +-------
>  drivers/iommu/irq_remapping.c                           | 2 +-
>  6 files changed, 6 insertions(+), 19 deletions(-)
>  create mode 100644 drivers/iommu/hyperv/Makefile
>  rename drivers/iommu/{hyperv-iommu.c => hyperv/hv-irq-remap.c} (99%)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index b539be153f6a..93a7105e9cef 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -11988,7 +11988,7 @@ F:	drivers/clocksource/hyperv_timer.c
>  F:	drivers/hid/hid-hyperv.c
>  F:	drivers/hv/
>  F:	drivers/input/serio/hyperv-keyboard.c
> -F:	drivers/iommu/hyperv-iommu.c
> +F:	drivers/iommu/hyperv/
>  F:	drivers/net/ethernet/microsoft/
>  F:	drivers/net/hyperv/
>  F:	drivers/pci/controller/pci-hyperv-intf.c
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index f86262b11416..1becc0f20222 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -351,15 +351,6 @@ config MTK_IOMMU_V1
>  
>  	  if unsure, say N here.
>  
> -config HYPERV_IOMMU
> -	bool "Hyper-V IRQ Handling"
> -	depends on HYPERV && X86
> -	select IOMMU_API
> -	default HYPERV
> -	help
> -	  Stub IOMMU driver to handle IRQs to support Hyper-V Linux
> -	  guest and root partitions.
> -
>  config VIRTIO_IOMMU
>  	tristate "Virtio IOMMU driver"
>  	depends on VIRTIO
> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
> index 0275821f4ef9..d9683422aecb 100644
> --- a/drivers/iommu/Makefile
> +++ b/drivers/iommu/Makefile
> @@ -4,6 +4,7 @@ obj-$(CONFIG_AMD_IOMMU) += amd/
>  obj-$(CONFIG_INTEL_IOMMU) += intel/
>  obj-$(CONFIG_RISCV_IOMMU) += riscv/
>  obj-$(CONFIG_GENERIC_PT) += generic_pt/fmt/
> +obj-$(CONFIG_HYPERV) += hyperv/
>  obj-$(CONFIG_IOMMU_API) += iommu.o
>  obj-$(CONFIG_IOMMU_SUPPORT) += iommu-pages.o
>  obj-$(CONFIG_IOMMU_API) += iommu-traces.o
> @@ -30,7 +31,6 @@ obj-$(CONFIG_TEGRA_IOMMU_SMMU) += tegra-smmu.o
>  obj-$(CONFIG_EXYNOS_IOMMU) += exynos-iommu.o
>  obj-$(CONFIG_FSL_PAMU) += fsl_pamu.o fsl_pamu_domain.o
>  obj-$(CONFIG_S390_IOMMU) += s390-iommu.o
> -obj-$(CONFIG_HYPERV_IOMMU) += hyperv-iommu.o
>  obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o
>  obj-$(CONFIG_IOMMU_SVA) += iommu-sva.o
>  obj-$(CONFIG_IOMMU_IOPF) += io-pgfault.o
> diff --git a/drivers/iommu/hyperv/Makefile
> b/drivers/iommu/hyperv/Makefile new file mode 100644
> index 000000000000..0053e00e08e6
> --- /dev/null
> +++ b/drivers/iommu/hyperv/Makefile
> @@ -0,0 +1,2 @@
> +# SPDX-License-Identifier: GPL-2.0
> +obj-$(CONFIG_IRQ_REMAP) += hv-irq-remap.o
Should the name be x86 specific? This file will never be built for ARM
because:
 CONFIG_IRQ_REMAP depends on:
 depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI

perhaps, hv-x86-irq-remap.c? hv-irq-remap.c sounds like a
generic Hyper-V IRQ-remapping backend and may be misleading once arm64
Hyper-V IOMMU/interrupt support grows under this directory.

> diff --git a/drivers/iommu/hyperv-iommu.c
> b/drivers/iommu/hyperv/hv-irq-remap.c similarity index 99%
> rename from drivers/iommu/hyperv-iommu.c
> rename to drivers/iommu/hyperv/hv-irq-remap.c
> index 479103261ae6..b34ee9589190 100644
> --- a/drivers/iommu/hyperv-iommu.c
> +++ b/drivers/iommu/hyperv/hv-irq-remap.c
> @@ -7,13 +7,11 @@
>   *
>   * Author : Lan Tianyu <Tianyu.Lan@microsoft.com>
>   */
> -
>  #include <linux/types.h>
>  #include <linux/interrupt.h>
>  #include <linux/irq.h>
>  #include <linux/iommu.h>
>  #include <linux/module.h>
> -
>  #include <asm/apic.h>
>  #include <asm/cpu.h>
>  #include <asm/hw_irq.h>
> @@ -22,9 +20,7 @@
>  #include <asm/hypervisor.h>
>  #include <asm/mshyperv.h>
>  
> -#include "irq_remapping.h"
> -
> -#ifdef CONFIG_IRQ_REMAP
> +#include "../irq_remapping.h"
>  
>  /*
>   * According 82093AA IO-APIC spec , IO APIC has a 24-entry Interrupt
> @@ -330,5 +326,3 @@ static const struct irq_domain_ops
> hyperv_root_ir_domain_ops = { .alloc =
> hyperv_root_irq_remapping_alloc, .free =
> hyperv_root_irq_remapping_free, };
> -
> -#endif
> diff --git a/drivers/iommu/irq_remapping.c
> b/drivers/iommu/irq_remapping.c index c2443659812a..41bf65e4ea88
> 100644 --- a/drivers/iommu/irq_remapping.c
> +++ b/drivers/iommu/irq_remapping.c
> @@ -108,7 +108,7 @@ int __init irq_remapping_prepare(void)
>  	else if (IS_ENABLED(CONFIG_AMD_IOMMU) &&
>  		 amd_iommu_irq_ops.prepare() == 0)
>  		remap_ops = &amd_iommu_irq_ops;
> -	else if (IS_ENABLED(CONFIG_HYPERV_IOMMU) &&
> +	else if (IS_ENABLED(CONFIG_HYPERV) &&
>  		 hyperv_irq_remap_ops.prepare() == 0)
>  		remap_ops = &hyperv_irq_remap_ops;
>  	else