linux-kernel - Re: [PATCH 1/4] drm/amdgpu: Fix compilation under UML

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Date:   Fri, 18 Feb 2022 11:39:05 -0500
From:   Felix Kuehling <felix.kuehling@....com>
To:     David Gow <davidgow@...gle.com>, Jeff Dike <jdike@...toit.com>,
        Richard Weinberger <richard@....at>,
        Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Brendan Higgins <brendanhiggins@...gle.com>,
        Randy Dunlap <rdunlap@...radead.org>
Cc:     linux-um@...ts.infradead.org, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, kunit-dev@...glegroups.com,
        linux-kselftest@...r.kernel.org, linux-rdma@...r.kernel.org,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] drm/amdgpu: Fix compilation under UML


Am 2022-02-18 um 02:57 schrieb David Gow:
> From: Randy Dunlap <rdunlap@...radead.org>
>
> cpuinfo_x86 and its associated macros are not available under ARCH=um,
> even though CONFIG_X86_64 is defined.
>
> This patch (and discussion) were originally posted here:
> https://lkml.org/lkml/2022/1/24/1547
>
> This produces the following build errors:
> ../drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_topology.c:1556:9: note: in expansion of macro ‘cpu_data’
>    return cpu_data(first_cpu_of_numa_node).apicid;
>           ^~~~~~~~
> ../drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_topology.c:1560:1: error: control reaches end of non-void function [-Werror=return-type]
>
> ../drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_crat.c: In function ‘kfd_fill_iolink_info_for_cpu’:
> ../arch/um/include/asm/processor-generic.h:103:19: error: called object is not a function or function pointer
>   #define cpu_data (&boot_cpu_data)
>                    ~^~~~~~~~~~~~~~~
> ../drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_crat.c:1688:27: note: in expansion of macro ‘cpu_data’
>    struct cpuinfo_x86 *c = &cpu_data(0);
>                             ^~~~~~~~
> ../drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_crat.c:1691:7: error: dereferencing pointer to incomplete type ‘struct cpuinfo_x86’
>    if (c->x86_vendor == X86_VENDOR_AMD)
>         ^~
> ../drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_crat.c:1691:23: error: ‘X86_VENDOR_AMD’ undeclared (first use in this function); did you mean ‘X86_VENDOR_ANY’?
>    if (c->x86_vendor == X86_VENDOR_AMD)
>                         ^~~~~~~~~~~~~~
>                         X86_VENDOR_ANY
>
> ../drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_crat.c: In function ‘kfd_create_vcrat_image_cpu’:
> ../drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_crat.c:1742:11: warning: unused variable ‘entries’ [-Wunused-variable]
>    uint32_t entries = 0;
>
> Signed-off-by: Randy Dunlap <rdunlap@...radead.org>
> Signed-off-by: David Gow <davidgow@...gle.com>
> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_crat.c     | 6 +++---
>   drivers/gpu/drm/amd/amdkfd/kfd_topology.c | 2 +-
>   2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_crat.c b/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
> index 9624bbe8b501..b1e2d117be3d 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
> @@ -1682,7 +1682,7 @@ static int kfd_fill_mem_info_for_cpu(int numa_node_id, int *avail_size,
>   	return 0;
>   }
>   
> -#ifdef CONFIG_X86_64
> +#if defined(CONFIG_X86_64) && !defined(CONFIG_UML)

I don't think it makes sense to compile a hardware device driver in a 
UML config. Instead of scattering UML #ifdefs through our code, I would 
recommend adding this to Kconfig:

--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -254,7 +254,7 @@ source "drivers/gpu/drm/radeon/Kconfig"
  
  config DRM_AMDGPU
         tristate "AMD GPU"
-       depends on DRM && PCI && MMU
+       depends on DRM && PCI && MMU && !UML
         select FW_LOADER
         select DRM_KMS_HELPER
         select DRM_SCHED

That would address patch 2 of this series as well.

Regards,
   Felix


>   static int kfd_fill_iolink_info_for_cpu(int numa_node_id, int *avail_size,
>   				uint32_t *num_entries,
>   				struct crat_subtype_iolink *sub_type_hdr)
> @@ -1741,7 +1741,7 @@ static int kfd_create_vcrat_image_cpu(void *pcrat_image, size_t *size)
>   	struct crat_subtype_generic *sub_type_hdr;
>   	int avail_size = *size;
>   	int numa_node_id;
> -#ifdef CONFIG_X86_64
> +#if defined(CONFIG_X86_64) && !defined(CONFIG_UML)
>   	uint32_t entries = 0;
>   #endif
>   	int ret = 0;
> @@ -1806,7 +1806,7 @@ static int kfd_create_vcrat_image_cpu(void *pcrat_image, size_t *size)
>   			sub_type_hdr->length);
>   
>   		/* Fill in Subtype: IO Link */
> -#ifdef CONFIG_X86_64
> +#if defined(CONFIG_X86_64) && !defined(CONFIG_UML)
>   		ret = kfd_fill_iolink_info_for_cpu(numa_node_id, &avail_size,
>   				&entries,
>   				(struct crat_subtype_iolink *)sub_type_hdr);
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_topology.c b/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
> index 948fbb39336e..b38fc530ffe2 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
> @@ -1552,7 +1552,7 @@ static int kfd_cpumask_to_apic_id(const struct cpumask *cpumask)
>   	first_cpu_of_numa_node = cpumask_first(cpumask);
>   	if (first_cpu_of_numa_node >= nr_cpu_ids)
>   		return -1;
> -#ifdef CONFIG_X86_64
> +#if defined(CONFIG_X86_64) && !defined(CONFIG_UML)
>   	return cpu_data(first_cpu_of_numa_node).apicid;
>   #else
>   	return first_cpu_of_numa_node;