linux-kernel - RE: [PATCH v13 019/113] KVM: TDX: create/destroy VM structure

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Message-ID: <DS0PR11MB63737EE10F2A42B1497DE325DC849@DS0PR11MB6373.namprd11.prod.outlook.com>
Date:   Fri, 24 Mar 2023 05:12:17 +0000
From:   "Wang, Wei W" <wei.w.wang@...el.com>
To:     "Wang, Lei4" <lei4.wang@...el.com>,
        "Yamahata, Isaku" <isaku.yamahata@...el.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "isaku.yamahata@...il.com" <isaku.yamahata@...il.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "Aktas, Erdem" <erdemaktas@...gle.com>,
        "Christopherson,, Sean" <seanjc@...gle.com>,
        "Shahar, Sagi" <sagis@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        "Huang, Kai" <kai.huang@...el.com>,
        Zhi Wang <zhi.wang.linux@...il.com>,
        "Sean Christopherson" <sean.j.christopherson@...el.com>
Subject: RE: [PATCH v13 019/113] KVM: TDX: create/destroy VM structure

On Friday, March 24, 2023 10:28 AM, Wang, Lei wrote:
> > +static int __tdx_td_init(struct kvm *kvm) {
> > +	struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
> > +	cpumask_var_t packages;
> > +	unsigned long *tdcs_pa = NULL;
> > +	unsigned long tdr_pa = 0;
> > +	unsigned long va;
> > +	int ret, i;
> > +	u64 err;
> > +
> > +	ret = tdx_guest_keyid_alloc();
> > +	if (ret < 0)
> > +		return ret;
> > +	kvm_tdx->hkid = ret;
> > +
> > +	va = __get_free_page(GFP_KERNEL_ACCOUNT);
> > +	if (!va)
> > +		goto free_hkid;
> > +	tdr_pa = __pa(va);
> > +
> > +	tdcs_pa = kcalloc(tdx_info.nr_tdcs_pages, sizeof(*kvm_tdx->tdcs_pa),
> > +			  GFP_KERNEL_ACCOUNT | __GFP_ZERO);
> > +	if (!tdcs_pa)
> > +		goto free_tdr;
> > +	for (i = 0; i < tdx_info.nr_tdcs_pages; i++) {
> > +		va = __get_free_page(GFP_KERNEL_ACCOUNT);
> > +		if (!va)
> > +			goto free_tdcs;
> > +		tdcs_pa[i] = __pa(va);
> > +	}
> > +
> > +	if (!zalloc_cpumask_var(&packages, GFP_KERNEL)) {
> > +		ret = -ENOMEM;
> > +		goto free_tdcs;
> > +	}
> > +	cpus_read_lock();
> > +	/*
> > +	 * Need at least one CPU of the package to be online in order to
> > +	 * program all packages for host key id.  Check it.
> > +	 */
> > +	for_each_present_cpu(i)
> > +		cpumask_set_cpu(topology_physical_package_id(i), packages);
> > +	for_each_online_cpu(i)
> > +		cpumask_clear_cpu(topology_physical_package_id(i),
> packages);
> > +	if (!cpumask_empty(packages)) {
> > +		ret = -EIO;
> > +		/*
> > +		 * Because it's hard for human operator to figure out the
> > +		 * reason, warn it.
> > +		 */
> > +		pr_warn("All packages need to have online CPU to create TD.
> Online CPU and retry.\n");
> > +		goto free_packages;
> > +	}
> > +
> > +	/*
> > +	 * Acquire global lock to avoid TDX_OPERAND_BUSY:
> > +	 * TDH.MNG.CREATE and other APIs try to lock the global Key Owner
> > +	 * Table (KOT) to track the assigned TDX private HKID.  It doesn't spin
> > +	 * to acquire the lock, returns TDX_OPERAND_BUSY instead, and let the
> > +	 * caller to handle the contention.  This is because of time limitation
> > +	 * usable inside the TDX module and OS/VMM knows better about
> process
> > +	 * scheduling.
> > +	 *
> > +	 * APIs to acquire the lock of KOT:
> > +	 * TDH.MNG.CREATE, TDH.MNG.KEY.FREEID, TDH.MNG.VPFLUSHDONE,
> and
> > +	 * TDH.PHYMEM.CACHE.WB.
> > +	 */
> > +	mutex_lock(&tdx_lock);
> > +	err = tdh_mng_create(tdr_pa, kvm_tdx->hkid);
> 
> In the latest (March 2023 ver.) Intel® TDX Module v1.5 ABI Specification, error
> code 0x80000203 represents TDX_RND_NO_ENTROPY:

This patchset is written for what's documented in the TDX 1.0 spec.
We'll update it for 1.5 later.