linux-kernel - Re: [PATCH v8 009/103] KVM: TDX: Initialize the TDX module when loading the KVM intel kernel module

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Message-ID: <20220825201600.GB2538772@ls.amr.corp.intel.com>
Date:   Thu, 25 Aug 2022 13:16:00 -0700
From:   Isaku Yamahata <isaku.yamahata@...il.com>
To:     "Huang, Kai" <kai.huang@...el.com>
Cc:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Yamahata, Isaku" <isaku.yamahata@...el.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "Shahar, Sagi" <sagis@...gle.com>,
        "Aktas, Erdem" <erdemaktas@...gle.com>,
        "isaku.yamahata@...il.com" <isaku.yamahata@...il.com>,
        "Christopherson,, Sean" <seanjc@...gle.com>
Subject: Re: [PATCH v8 009/103] KVM: TDX: Initialize the TDX module when
 loading the KVM intel kernel module

On Mon, Aug 08, 2022 at 10:41:27AM +0000,
"Huang, Kai" <kai.huang@...el.com> wrote:

> > +int __init tdx_module_setup(void)
> > +{
> > +	const struct tdsysinfo_struct *tdsysinfo;
> > +	int ret = 0;
> > +
> > +	BUILD_BUG_ON(sizeof(*tdsysinfo) != 1024);
> > +	BUILD_BUG_ON(TDX_MAX_NR_CPUID_CONFIGS != 37);
> > +
> > +	ret = tdx_init();
> > +	if (ret) {
> > +		pr_info("Failed to initialize TDX module.\n");
> > +		return ret;
> > +	}
> > +
> > +	tdsysinfo = tdx_get_sysinfo();
> > +	if (tdsysinfo->num_cpuid_config > TDX_MAX_NR_CPUID_CONFIGS)
> > +		return -EIO;
> > +
> > +	tdx_caps = (struct tdx_capabilities) {
> > +		.tdcs_nr_pages = tdsysinfo->tdcs_base_size / PAGE_SIZE,
> > +		/*
> > +		 * TDVPS = TDVPR(4K page) + TDVPX(multiple 4K pages).
> > +		 * -1 for TDVPR.
> > +		 */
> > +		.tdvpx_nr_pages = tdsysinfo->tdvps_base_size / PAGE_SIZE - 1,
> > +		.attrs_fixed0 = tdsysinfo->attributes_fixed0,
> > +		.attrs_fixed1 = tdsysinfo->attributes_fixed1,
> > +		.xfam_fixed0 =	tdsysinfo->xfam_fixed0,
> > +		.xfam_fixed1 = tdsysinfo->xfam_fixed1,
> > +		.nr_cpuid_configs = tdsysinfo->num_cpuid_config,
> > +	};
> > +	if (!memcpy(tdx_caps.cpuid_configs, tdsysinfo->cpuid_configs,
> > +			tdsysinfo->num_cpuid_config *
> > +			sizeof(struct tdx_cpuid_config)))
> > +		return -EIO;
> > +
> > +	return 0;
> > +}
> > +
> > +int __init tdx_hardware_setup(struct kvm_x86_ops *x86_ops)
> 
> Function argument isn't used.
> 
> > +{
> > +	if (!enable_ept) {
> > +		pr_warn("Cannot enable TDX with EPT disabled\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	if (!platform_tdx_enabled()) {
> > +		pr_warn("Cannot enable TDX on TDX disabled platform\n");
> > +		return -ENODEV;
> > +	}
> 
> I am not sure whether this is necessary, as tdx_init() will call it internally
> anyway.
> 
> > +
> > +	pr_info("kvm: TDX is supported. x86 phys bits %d\n",
> > +		boot_cpu_data.x86_phys_bits);
> 
> Is it a little early to say "TDX is supported" before tdx_init() is called?
> 
> I don't think the whole tdx_hardware_setup() is even necessary?  Looks nothing
> is serious here anyway, and all staff can be done in tdx_module_setup().

With the reorganize of kvm initialization[1], we have only one callback
(kvm_arch_hardware_setup()).  And yes, the message should be output after
tdx_init().

[1] https://lore.kernel.org/lkml/cover.1660974106.git.isaku.yamahata@intel.com/

-- 
Isaku Yamahata <isaku.yamahata@...il.com>