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Message-ID: <763ee03a-817d-4833-b42f-e5b4bd25dc7f@linuxfoundation.org>
Date: Thu, 25 Apr 2024 10:22:11 -0600
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Subject: Re: [PATCH v13 25/35] KVM: selftests: Convert lib's mem regions to
 KVM_SET_USER_MEMORY_REGION2
To: Sean Christopherson <seanjc@google.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>, Shuah Khan <shuah@kernel.org>,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
 Paolo Bonzini <pbonzini@redhat.com>, Marc Zyngier <maz@kernel.org>,
 Oliver Upton <oliver.upton@linux.dev>, Huacai Chen <chenhuacai@kernel.org>,
 Michael Ellerman <mpe@ellerman.id.au>, Anup Patel <anup@brainfault.org>,
 Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt
 <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu>,
 Alexander Viro <viro@zeniv.linux.org.uk>,
 Christian Brauner <brauner@kernel.org>,
 "Matthew Wilcox (Oracle)" <willy@infradead.org>,
 Andrew Morton <akpm@linux-foundation.org>, kvm@vger.kernel.org,
 linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
 linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
 kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org,
 linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
 linux-kernel@vger.kernel.org, Xiaoyao Li <xiaoyao.li@intel.com>,
 Xu Yilun <yilun.xu@intel.com>, Chao Peng <chao.p.peng@linux.intel.com>,
 Fuad Tabba <tabba@google.com>, Jarkko Sakkinen <jarkko@kernel.org>,
 Anish Moorthy <amoorthy@google.com>, David Matlack <dmatlack@google.com>,
 Yu Zhang <yu.c.zhang@linux.intel.com>,
 Isaku Yamahata <isaku.yamahata@intel.com>, =?UTF-8?B?TWlja2HDq2wgU2FsYcO8?=
 =?UTF-8?Q?n?= <mic@digikod.net>, Vlastimil Babka <vbabka@suse.cz>,
 Vishal Annapurve <vannapurve@google.com>,
 Ackerley Tng <ackerleytng@google.com>,
 Maciej Szmigiero <mail@maciej.szmigiero.name>,
 David Hildenbrand <david@redhat.com>, Quentin Perret <qperret@google.com>,
 Michael Roth <michael.roth@amd.com>, Wang <wei.w.wang@intel.com>,
 Liam Merwick <liam.merwick@oracle.com>,
 Isaku Yamahata <isaku.yamahata@gmail.com>,
 "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
 Naresh Kamboju <naresh.kamboju@linaro.org>,
 Anders Roxell <anders.roxell@linaro.org>,
 Benjamin Copeland <ben.copeland@linaro.org>,
 Shuah Khan <skhan@linuxfoundation.org>
References: <20231027182217.3615211-1-seanjc@google.com>
 <20231027182217.3615211-26-seanjc@google.com>
 <69ae0694-8ca3-402c-b864-99b500b24f5d@moroto.mountain>
 <3848a9ad-07aa-48da-a2b7-264c4a990b5b@linuxfoundation.org>
 <ZipyPYR8Nv_usoU4@google.com>
Content-Language: en-US
From: Shuah Khan <skhan@linuxfoundation.org>
In-Reply-To: <ZipyPYR8Nv_usoU4@google.com>
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On 4/25/24 09:09, Sean Christopherson wrote:
> On Thu, Apr 25, 2024, Shuah Khan wrote:
>> On 4/25/24 08:12, Dan Carpenter wrote:
>>> On Fri, Oct 27, 2023 at 11:22:07AM -0700, Sean Christopherson wrote:
>>>> Use KVM_SET_USER_MEMORY_REGION2 throughout KVM's selftests library so that
>>>> support for guest private memory can be added without needing an entirely
>>>> separate set of helpers.
>>>>
>>>> Note, this obviously makes selftests backwards-incompatible with older KVM
>>>     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>>> versions from this point forward.
>>>     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>>
>>> Is there a way we could disable the tests on older kernels instead of
>>> making them fail?  Check uname or something?  There is probably a
>>> standard way to do this...  It's these tests which fail.
>>
>> They shouldn't fail - the tests should be skipped on older kernels.
> 
> Ah, that makes sense.  Except for a few outliers that aren't all that interesting,
> all KVM selftests create memslots, so I'm tempted to just make it a hard requirement
> to spare us headache, e.g.
> 
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index b2262b5fad9e..4b2038b1f11f 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -2306,6 +2306,9 @@ void __attribute((constructor)) kvm_selftest_init(void)
>          /* Tell stdout not to buffer its content. */
>          setbuf(stdout, NULL);
>   
> +       __TEST_REQUIRE(kvm_has_cap(KVM_CAP_USER_MEMORY2),
> +                      "KVM selftests from v6.8+ require KVM_SET_USER_MEMORY_REGION2");
> +
>          kvm_selftest_arch_init();
>   }
> 
> --
> 
> but it's also easy enough to be more precise and skip only those that actually
> create memslots.

This is approach is what is recommended in kselfest document. Rubn as many tests
as possible and skip the ones that can't be run due to unmet dependencies.

> 
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index b2262b5fad9e..b21152adf448 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -944,6 +944,9 @@ int __vm_set_user_memory_region2(struct kvm_vm *vm, uint32_t slot, uint32_t flag
>                  .guest_memfd_offset = guest_memfd_offset,
>          };
>   
> +       __TEST_REQUIRE(kvm_has_cap(KVM_CAP_USER_MEMORY2),
> +                      "KVM selftests from v6.8+ require KVM_SET_USER_MEMORY_REGION2");
> +
>          return ioctl(vm->fd, KVM_SET_USER_MEMORY_REGION2, &region);
>   }
>   
> @@ -970,6 +973,9 @@ void vm_mem_add(struct kvm_vm *vm, enum vm_mem_backing_src_type src_type,
>          size_t mem_size = npages * vm->page_size;
>          size_t alignment;
>   
> +       __TEST_REQUIRE(kvm_has_cap(KVM_CAP_USER_MEMORY2),
> +                      "KVM selftests from v6.8+ require KVM_SET_USER_MEMORY_REGION2");
> +
>          TEST_ASSERT(vm_adjust_num_guest_pages(vm->mode, npages) == npages,
>                  "Number of guest pages is not compatible with the host. "
>                  "Try npages=%d", vm_adjust_num_guest_pages(vm->mode, npages));
> --

thanks,
-- Shuah