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Date:   Tue, 12 Dec 2023 09:18:14 -0800
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References: <20231130111804.2227570-1-zhaotianrui@loongson.cn>
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Message-ID: <ZXiV1rMrXY0hNgvZ@google.com>
Subject: Re: [PATCH v5 1/4] KVM: selftests: Add KVM selftests header files for LoongArch
From:   Sean Christopherson <seanjc@google.com>
To:     zhaotianrui <zhaotianrui@loongson.cn>
Cc:     Shuah Khan <shuah@kernel.org>, Paolo Bonzini <pbonzini@redhat.com>,
        linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        Vishal Annapurve <vannapurve@google.com>,
        Huacai Chen <chenhuacai@kernel.org>,
        WANG Xuerui <kernel@xen0n.name>, loongarch@lists.linux.dev,
        Peter Xu <peterx@redhat.com>,
        Vipin Sharma <vipinsh@google.com>, maobibo@loongson.cn
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On Tue, Dec 12, 2023, zhaotianrui wrote:
> Hi, Sean:
>=20
> I want to change the definition of=C2=A0 DEFAULT_GUEST_TEST_MEM in the co=
mmon
> file "memstress.h", like this:
>=20
>  /* Default guest test virtual memory offset */
> +#ifndef DEFAULT_GUEST_TEST_MEM
>  #define DEFAULT_GUEST_TEST_MEM		0xc0000000
> +#endif
>=20
> As this address should be re-defined in LoongArch headers.

Why?  E.g. is 0xc0000000 unconditionally reserved, not guaranteed to be val=
id,
something else?

> So, do you have any suggesstion?

Hmm, I think ideally kvm_util_base.h would define a range of memory that ca=
n be
used by tests for arbitrary data.  Multiple tests use 0xc0000000, which is =
not
entirely arbitrary, i.e. it doesn't _need_ to be 0xc0000000, but 0xc0000000=
 is
convenient because it's 32-bit addressable and doesn't overlap reserved are=
as in
other architectures.