linux-kernel - Re: [PATCH v7 7/8] iommu/vt-d: Add nested domain allocation

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Message-ID: <04b3cc65-fcb0-4a33-b012-0085e7886e33@intel.com>
Date:   Wed, 25 Oct 2023 17:02:19 +0800
From:   Yi Liu <yi.l.liu@...el.com>
To:     Jason Gunthorpe <jgg@...dia.com>
CC:     <joro@...tes.org>, <alex.williamson@...hat.com>,
        <kevin.tian@...el.com>, <robin.murphy@....com>,
        <baolu.lu@...ux.intel.com>, <cohuck@...hat.com>,
        <eric.auger@...hat.com>, <nicolinc@...dia.com>,
        <kvm@...r.kernel.org>, <mjrosato@...ux.ibm.com>,
        <chao.p.peng@...ux.intel.com>, <yi.y.sun@...ux.intel.com>,
        <peterx@...hat.com>, <jasowang@...hat.com>,
        <shameerali.kolothum.thodi@...wei.com>, <lulu@...hat.com>,
        <suravee.suthikulpanit@....com>, <iommu@...ts.linux.dev>,
        <linux-kernel@...r.kernel.org>, <linux-kselftest@...r.kernel.org>,
        <zhenzhong.duan@...el.com>, <joao.m.martins@...cle.com>
Subject: Re: [PATCH v7 7/8] iommu/vt-d: Add nested domain allocation

On 2023/10/25 07:03, Jason Gunthorpe wrote:
> On Tue, Oct 24, 2023 at 08:14:11AM -0700, Yi Liu wrote:
>> From: Lu Baolu <baolu.lu@...ux.intel.com>
>>
>> This adds the support for IOMMU_HWPT_DATA_VTD_S1 type. And 'nested_parent'
>> is added to mark the nested parent domain to sanitize the input parent domain.
>>
>> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
>> Signed-off-by: Yi Liu <yi.l.liu@...el.com>
>> ---
>>   drivers/iommu/intel/iommu.c | 67 +++++++++++++++++++++++++------------
>>   drivers/iommu/intel/iommu.h |  1 +
>>   2 files changed, 46 insertions(+), 22 deletions(-)
> 
> I think it should be written like this:
> 
> @@ -4077,38 +4082,39 @@ intel_iommu_domain_alloc_user(struct device *dev, u32 flags,
>   			      struct iommu_domain *parent,
>   			      const struct iommu_user_data *user_data)
>   {
> +	struct device_domain_info *info = dev_iommu_priv_get(dev);
> +	bool dirty_tracking = flags & IOMMU_HWPT_ALLOC_DIRTY_TRACKING;
> +	bool nested_parent = flags & IOMMU_HWPT_ALLOC_NEST_PARENT;
> +	struct intel_iommu *iommu = info->iommu;
>   	struct iommu_domain *domain;
> -	struct intel_iommu *iommu;
> -	bool dirty_tracking;
> +
> +	/* Must be NESTING domain */
> +	if (parent) {
> +		if (!nested_supported(iommu) || flags)
> +			return ERR_PTR(-EOPNOTSUPP);
> +		return intel_nested_domain_alloc(parent, user_data);
> +	}
>   
>   	if (flags &
>   	    (~(IOMMU_HWPT_ALLOC_NEST_PARENT | IOMMU_HWPT_ALLOC_DIRTY_TRACKING)))
>   		return ERR_PTR(-EOPNOTSUPP);
> -
> -	if (parent || user_data)
> +	if (nested_parent && !nested_supported(iommu))
>   		return ERR_PTR(-EOPNOTSUPP);
> -
> -	iommu = device_to_iommu(dev, NULL, NULL);
> -	if (!iommu)
> -		return ERR_PTR(-ENODEV);
> -
> -	if ((flags & IOMMU_HWPT_ALLOC_NEST_PARENT) && !nested_supported(iommu))
> -		return ERR_PTR(-EOPNOTSUPP);
> -
> -	dirty_tracking = (flags & IOMMU_HWPT_ALLOC_DIRTY_TRACKING);
> -	if (dirty_tracking && !ssads_supported(iommu))
> +	if (user_data || (dirty_tracking && !ssads_supported(iommu)))
>   		return ERR_PTR(-EOPNOTSUPP);
>   
>   	/*
> -	 * domain_alloc_user op needs to fully initialize a domain
> -	 * before return, so uses iommu_domain_alloc() here for
> -	 * simple.
> +	 * domain_alloc_user op needs to fully initialize a domain before
> +	 * return, so uses iommu_domain_alloc() here for simple.
>   	 */
>   	domain = iommu_domain_alloc(dev->bus);
>   	if (!domain)
> -		domain = ERR_PTR(-ENOMEM);
> +		return ERR_PTR(-ENOMEM);
>   
> -	if (!IS_ERR(domain) && dirty_tracking) {
> +	if (nested_parent)
> +		to_dmar_domain(domain)->nested_parent = true;
> +
> +	if (dirty_tracking) {
>   		if (to_dmar_domain(domain)->use_first_level) {
>   			iommu_domain_free(domain);
>   			return ERR_PTR(-EOPNOTSUPP);
> @@ -4849,6 +4855,7 @@ static void *intel_iommu_hw_info(struct device *dev, u32 *length, u32 *type)
>   	if (!vtd)
>   		return ERR_PTR(-ENOMEM);
>   
> +	vtd->flags = IOMMU_HW_INFO_VTD_ERRATA_772415_SPR17;

this flag is introduced in [8/8]. still make sense to keep it there?

>   	vtd->cap_reg = iommu->cap;
>   	vtd->ecap_reg = iommu->ecap;
>   	*length = sizeof(*vtd);
> diff --git a/drivers/iommu/intel/nested.c b/drivers/iommu/intel/nested.c
> index d9197dd72748b1..b5a5563ab32c6b 100644
> --- a/drivers/iommu/intel/nested.c
> +++ b/drivers/iommu/intel/nested.c
> @@ -78,13 +78,21 @@ static const struct iommu_domain_ops intel_nested_domain_ops = {
>   	.free			= intel_nested_domain_free,
>   };
>   
> -struct iommu_domain *intel_nested_domain_alloc(struct iommu_domain *s2_domain,
> +struct iommu_domain *intel_nested_domain_alloc(struct iommu_domain *parent,
>   					       const struct iommu_user_data *user_data)
>   {
> +	struct dmar_domain *s2_domain = to_dmar_domain(parent);
>   	struct iommu_hwpt_vtd_s1 vtd;
>   	struct dmar_domain *domain;
>   	int ret;
>   
> +	/* Must be nested domain */
> +	if (user_data->type != IOMMU_HWPT_DATA_VTD_S1)
> +		return ERR_PTR(-EOPNOTSUPP);
> +	if (parent->ops != intel_iommu_ops.default_domain_ops ||
> +	    !s2_domain->nested_parent)
> +		return ERR_PTR(-EINVAL);
> +
>   	ret = iommu_copy_struct_from_user(&vtd, user_data,
>   					  IOMMU_HWPT_DATA_VTD_S1, __reserved);
>   	if (ret)
> @@ -95,7 +103,7 @@ struct iommu_domain *intel_nested_domain_alloc(struct iommu_domain *s2_domain,
>   		return ERR_PTR(-ENOMEM);
>   
>   	domain->use_first_level = true;
> -	domain->s2_domain = to_dmar_domain(s2_domain);
> +	domain->s2_domain = s2_domain;
>   	domain->s1_pgtbl = vtd.pgtbl_addr;
>   	domain->s1_cfg = vtd;
>   	domain->domain.ops = &intel_nested_domain_ops;

-- 
Regards,
Yi Liu