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Date:   Mon, 07 Aug 2023 23:20:15 +0000
In-Reply-To: <20230718234512.1690985-29-seanjc@google.com> (message from Sean
 Christopherson on Tue, 18 Jul 2023 16:45:11 -0700)
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Subject: Re: [RFC PATCH v11 28/29] KVM: selftests: Add basic selftest for guest_memfd()
From:   Ackerley Tng <ackerleytng@google.com>
To:     Sean Christopherson <seanjc@google.com>
Cc:     pbonzini@redhat.com, maz@kernel.org, oliver.upton@linux.dev,
        chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org,
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Sean Christopherson <seanjc@google.com> writes:

> Add a selftest to verify the basic functionality of guest_memfd():
>
> + file descriptor created with the guest_memfd() ioctl does not allow
>   read/write/mmap operations
> + file size and block size as returned from fstat are as expected
> + fallocate on the fd checks that offset/length on
>   fallocate(FALLOC_FL_PUNCH_HOLE) should be page aligned
>

> <snip>

> +
> +static void test_fallocate(int fd, size_t page_size, size_t total_size)
> +{
> +	int ret;
> +
> +	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE, 0, total_size);
> +	TEST_ASSERT(!ret, "fallocate with aligned offset and size should succeed");
> +
> +	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
> +			page_size - 1, page_size);
> +	TEST_ASSERT(ret, "fallocate with unaligned offset should fail");
> +
> +	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE, total_size, page_size);
> +	TEST_ASSERT(ret, "fallocate beginning at total_size should fail");
> +
> +	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE, total_size + page_size, page_size);
> +	TEST_ASSERT(ret, "fallocate beginning at total_size should fail");

This should be

TEST_ASSERT(ret, "fallocate beginning after total_size should fail");

> +
> +	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
> +			total_size, page_size);
> +	TEST_ASSERT(!ret, "fallocate(PUNCH_HOLE) at total_size should succeed");
> +
> +	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
> +			total_size + page_size, page_size);
> +	TEST_ASSERT(!ret, "fallocate(PUNCH_HOLE) after total_size should succeed");
> +
> +	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
> +			page_size, page_size - 1);
> +	TEST_ASSERT(ret, "fallocate with unaligned size should fail");
> +
> +	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
> +			page_size, page_size);
> +	TEST_ASSERT(!ret, "fallocate(PUNCH_HOLE) with aligned offset and size should succeed");
> +
> +	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE, page_size, page_size);
> +	TEST_ASSERT(!ret, "fallocate to restore punched hole should succeed");
> +}

> <snip>