linux-kernel - Re: [PATCH v3 2/3] KVM: selftests: Enable pre_fault_memory

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Message-ID: <aTMXYZgZM3QvZP2i@google.com>
Date: Fri, 5 Dec 2025 17:33:21 +0000
From: Vincent Donnefort <vdonnefort@...gle.com>
To: Jack Thomson <jackabt.amazon@...il.com>
Cc: maz@...nel.org, oliver.upton@...ux.dev, pbonzini@...hat.com,
	joey.gouly@....com, suzuki.poulose@....com, yuzenghui@...wei.com,
	catalin.marinas@....com, will@...nel.org, shuah@...nel.org,
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
	linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
	isaku.yamahata@...el.com, xmarcalx@...zon.co.uk,
	kalyazin@...zon.co.uk, jackabt@...zon.com
Subject: Re: [PATCH v3 2/3] KVM: selftests: Enable pre_fault_memory_test for
 arm64

On Wed, Nov 19, 2025 at 03:49:09PM +0000, Jack Thomson wrote:
> From: Jack Thomson <jackabt@...zon.com>
> 
> Enable the pre_fault_memory_test to run on arm64 by making it work with
> different guest page sizes and testing multiple guest configurations.
> 
> Update the test_assert to compare against the UCALL_EXIT_REASON, for
> portability, as arm64 exits with KVM_EXIT_MMIO while x86 uses
> KVM_EXIT_IO.
> 
> Signed-off-by: Jack Thomson <jackabt@...zon.com>
> ---
>  tools/testing/selftests/kvm/Makefile.kvm      |  1 +
>  .../selftests/kvm/pre_fault_memory_test.c     | 78 ++++++++++++++-----
>  2 files changed, 58 insertions(+), 21 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
> index 148d427ff24b..0ddd8db60197 100644
> --- a/tools/testing/selftests/kvm/Makefile.kvm
> +++ b/tools/testing/selftests/kvm/Makefile.kvm
> @@ -183,6 +183,7 @@ TEST_GEN_PROGS_arm64 += memslot_perf_test
>  TEST_GEN_PROGS_arm64 += mmu_stress_test
>  TEST_GEN_PROGS_arm64 += rseq_test
>  TEST_GEN_PROGS_arm64 += steal_time
> +TEST_GEN_PROGS_arm64 += pre_fault_memory_test
>  
>  TEST_GEN_PROGS_s390 = $(TEST_GEN_PROGS_COMMON)
>  TEST_GEN_PROGS_s390 += s390/memop
> diff --git a/tools/testing/selftests/kvm/pre_fault_memory_test.c b/tools/testing/selftests/kvm/pre_fault_memory_test.c
> index f04768c1d2e4..674931e7bb3a 100644
> --- a/tools/testing/selftests/kvm/pre_fault_memory_test.c
> +++ b/tools/testing/selftests/kvm/pre_fault_memory_test.c
> @@ -11,19 +11,29 @@
>  #include <kvm_util.h>
>  #include <processor.h>
>  #include <pthread.h>
> +#include <guest_modes.h>
>  
>  /* Arbitrarily chosen values */
> -#define TEST_SIZE		(SZ_2M + PAGE_SIZE)
> -#define TEST_NPAGES		(TEST_SIZE / PAGE_SIZE)

After applying on top of the base commit
8a4821412cf2c1429fffa07c012dd150f2edf78c, it does not build.

That TEST_NPAGES seems to still be used in delete_slot_worker(). I believe
that's because of

  "KVM: selftests: Test prefault memory during concurrent memslot removal"

Related issues with the pre_fault_memory() prototype.

Is that the correct base-commit or shall I use something else?

> +#define TEST_BASE_SIZE		SZ_2M
>  #define TEST_SLOT		10
>

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