linux-kernel - Re: [PATCH RFC v7 10/64] KVM: SEV: Populate private memory fd during LAUNCH_UPDATE

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Message-ID: <Y8Gs0l1k4L96dP5V@zn.tnic>
Date:   Fri, 13 Jan 2023 20:11:14 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Michael Roth <michael.roth@....com>
Cc:     kvm@...r.kernel.org, linux-coco@...ts.linux.dev,
        linux-mm@...ck.org, linux-crypto@...r.kernel.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        jroedel@...e.de, thomas.lendacky@....com, hpa@...or.com,
        ardb@...nel.org, pbonzini@...hat.com, seanjc@...gle.com,
        vkuznets@...hat.com, wanpengli@...cent.com, jmattson@...gle.com,
        luto@...nel.org, dave.hansen@...ux.intel.com, slp@...hat.com,
        pgonda@...gle.com, peterz@...radead.org,
        srinivas.pandruvada@...ux.intel.com, rientjes@...gle.com,
        dovmurik@...ux.ibm.com, tobin@....com, vbabka@...e.cz,
        kirill@...temov.name, ak@...ux.intel.com, tony.luck@...el.com,
        marcorr@...gle.com, sathyanarayanan.kuppuswamy@...ux.intel.com,
        alpergun@...gle.com, dgilbert@...hat.com, jarkko@...nel.org,
        ashish.kalra@....com, harald@...fian.com,
        Vishal Annapurve <vannapurve@...gle.com>
Subject: Re: [PATCH RFC v7 10/64] KVM: SEV: Populate private memory fd during
 LAUNCH_UPDATE_DATA

On Wed, Dec 14, 2022 at 01:40:02PM -0600, Michael Roth wrote:
> From: Vishal Annapurve <vannapurve@...gle.com>
> 
> This change adds handling of HVA ranges to copy contents

s/This change adds handling of/Handle/

> +static int sev_launch_update_priv_gfn_handler(struct kvm *kvm,
> +					      struct kvm_gfn_range *range,
> +					      struct kvm_sev_cmd *argp)
> +{
> +	struct sev_data_launch_update_data data;
> +	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> +	gfn_t gfn;
> +	kvm_pfn_t pfn;
> +	struct kvm_memory_slot *memslot = range->slot;
> +	int ret = 0;
> +
> +	data.reserved = 0;
> +	data.handle = sev->handle;
> +
> +	for (gfn = range->start; gfn < range->end; gfn++) {
> +		int order;
> +		void *kvaddr;
> +
> +		ret = kvm_restricted_mem_get_pfn(memslot, gfn, &pfn, &order);
> +		if (ret)
> +			return ret;
> +
> +		kvaddr = pfn_to_kaddr(pfn);
> +		if (!virt_addr_valid(kvaddr)) {
> +			pr_err("Invalid kvaddr 0x%llx\n", (uint64_t)kvaddr);

Is that some debugging help leftover or what is that printk issued for?

> +			ret = -EINVAL;
> +			goto e_ret;
> +		}
> +
> +		ret = kvm_read_guest_page(kvm, gfn, kvaddr, 0, PAGE_SIZE);
> +		if (ret) {
> +			pr_err("guest read failed 0x%x\n", ret);
> +			goto e_ret;
> +		}
> +
> +		if (!this_cpu_has(X86_FEATURE_SME_COHERENT))

check_for_deprecated_apis: WARNING: arch/x86/kvm/svm/sev.c:602: Do not use this_cpu_has() - use cpu_feature_enabled() instead.

> +			clflush_cache_range(kvaddr, PAGE_SIZE);
> +
> +		data.len = PAGE_SIZE;
> +		data.address = __sme_set(pfn << PAGE_SHIFT);
> +		ret = sev_issue_cmd(kvm, SEV_CMD_LAUNCH_UPDATE_DATA, &data, &argp->error);
> +		if (ret)
> +			goto e_ret;
> +		kvm_release_pfn_clean(pfn);
> +	}
> +	kvm_vm_set_region_attr(kvm, range->start, range->end,
> +		true /* priv_attr */);

No need to break that line.

> +
> +e_ret:
> +	return ret;
> +}
> +
> +static int sev_launch_update_gfn_handler(struct kvm *kvm, struct kvm_gfn_range *range,
> +					 void *data)
> +{
> +	struct kvm_sev_cmd *argp = (struct kvm_sev_cmd *)data;
> +
> +	if (kvm_slot_can_be_private(range->slot))
> +		return sev_launch_update_priv_gfn_handler(kvm, range, argp);
> +
> +	return sev_launch_update_shared_gfn_handler(kvm, range, argp);
> +}
> +
> +static int sev_launch_update_data(struct kvm *kvm,
> +		struct kvm_sev_cmd *argp)
> +{
> +	struct kvm_sev_launch_update_data params;
> +
> +	if (!sev_guest(kvm))
> +		return -ENOTTY;
> +
> +	if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data, sizeof(params)))
> +		return -EFAULT;

Not gonna check those user-supplied values for sanity?

Or is this check

        if (WARN_ON_ONCE(hva_end <= hva_start))
                return -EINVAL;

in kvm_vm_do_hva_range_op() enough?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette