linux-kernel - Re: [PATCH] x86/vmware: Add TDX hypercall support

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Date:   Thu, 7 Dec 2023 09:12:41 -0800
From:   Dave Hansen <dave.hansen@...el.com>
To:     Alexey Makhalov <alexey.makhalov@...adcom.com>,
        linux-kernel@...r.kernel.org, virtualization@...ts.linux.dev,
        hpa@...or.com, dave.hansen@...ux.intel.co, bp@...en8.d,
        mingo@...hat.com, tglx@...utronix.de, dave.hansen@...ux.intel.com
Cc:     x86@...nel.org, netdev@...r.kernel.org, richardcochran@...il.com,
        linux-input@...r.kernel.org, dmitry.torokhov@...il.com,
        zackr@...are.com, linux-graphics-maintainer@...are.com,
        pv-drivers@...are.com, namit@...are.com, timothym@...are.com,
        akaher@...are.com, jsipek@...are.com,
        dri-devel@...ts.freedesktop.org, daniel@...ll.ch,
        airlied@...il.com, tzimmermann@...e.de, mripard@...nel.org,
        maarten.lankhorst@...ux.intel.com, horms@...nel.org
Subject: Re: [PATCH] x86/vmware: Add TDX hypercall support

On 12/5/23 23:15, Alexey Makhalov wrote:
> +#ifdef CONFIG_INTEL_TDX_GUEST
> +/* Export tdx hypercall and allow it only for VMware guests. */
> +void vmware_tdx_hypercall_args(struct tdx_module_args *args)
> +{
> +	if (hypervisor_is_type(X86_HYPER_VMWARE))
> +		__tdx_hypercall(args);
> +}
> +EXPORT_SYMBOL_GPL(vmware_tdx_hypercall_args);
> +#endif

I think this is still too generic.  This still allows anything setting
X86_HYPER_VMWARE to make any TDX hypercall.

I'd *much* rather you export something like vmware_tdx_hypercall() or
even the high-level calls like hypervisor_ppn_reset_all().  The higher
level and more specialized the interface, the less likely it is to be
abused.