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Date:   Tue, 5 Dec 2023 16:11:29 -0800
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Subject: Re: [PATCH v2 6/6] x86/vmware: Add TDX hypercall support
To:     Dave Hansen <dave.hansen@intel.com>,
        Borislav Petkov <bp@alien8.de>,
        Alexey Makhalov <amakhalov@vmware.com>
Cc:     linux-kernel@vger.kernel.org, virtualization@lists.linux.dev,
        hpa@zytor.com, dave.hansen@linux.intel.co, bp@alien8.d,
        mingo@redhat.com, tglx@linutronix.de, x86@kernel.org,
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        pv-drivers@vmware.com, namit@vmware.com, timothym@vmware.com,
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        airlied@gmail.com, tzimmermann@suse.de, mripard@kernel.org,
        maarten.lankhorst@linux.intel.com, horms@kernel.org
References: <20231122233058.185601-8-amakhalov@vmware.com>
 <20231201232452.220355-1-amakhalov@vmware.com>
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From:   Alexey Makhalov <alexey.makhalov@broadcom.com>
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On 12/5/23 3:03 PM, Dave Hansen wrote:
> On 12/5/23 13:41, Alexey Makhalov wrote:
>>> I don't really like it much.=C2=A0 This does a generic thing (make a TD=
X
>>> hypercall) with a specific name ("vmware_").=C2=A0 If you want to make =
an
>>> argument that a certain chunk of the __tdx_hypercall() space is just fo=
r
>>> VMWare and you also add a VMWare-specific check and then export *that*,
>>> it might be acceptable.
>>>
>>> But I don't want random modules able to make random, unrestricted TDX
>>> hypercalls.=C2=A0 That's asking for trouble.
>>
>> Considering exporting of __tdx_hypercall for random modules is not an
>> option, what VMware specific checks you are suggesting?
>=20
> Make sure it can only be called running on VMWare guests.  A check for
> X86_HYPER_VMWARE seems simple enough.
>=20
> Second, unless the space is *HUGE*, you want to be exporting things like
> __vmware_platform() or vmware_legacy_x2apic_available(), *NOT* the
> underlying hypercall functions.
>=20
> We want to make sure that the interfaces are well defined and bounded.

Thanks Dave and Tim for your suggestions. I followed Dave recommendation=20
to have a simple check for X86_HYPER_VMWARE.

Please review patch 6, which I'll send shortly.

Thanks,
--Alexey

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