linux-kernel - Re: [PATCH v2 2/4] iommu/vt-d: Enable write protect propagation from guest

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Date:   Wed, 3 Mar 2021 12:57:17 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>,
        iommu@...ts.linux-foundation.org, Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>
Cc:     baolu.lu@...ux.intel.com, Yi Liu <yi.l.liu@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        Eric Auger <eric.auger@...hat.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Sanjay Kumar <sanjay.k.kumar@...el.com>
Subject: Re: [PATCH v2 2/4] iommu/vt-d: Enable write protect propagation from
 guest

On 3/2/21 6:13 PM, Jacob Pan wrote:
> Write protect bit, when set, inhibits supervisor writes to the read-only
> pages. In guest supervisor shared virtual addressing (SVA), write-protect
> should be honored upon guest bind supervisor PASID request.
> 
> This patch extends the VT-d portion of the IOMMU UAPI to include WP bit.
> WPE bit of the  supervisor PASID entry will be set to match CPU CR0.WP bit.
> 
> Signed-off-by: Sanjay Kumar <sanjay.k.kumar@...el.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> ---
>   drivers/iommu/intel/pasid.c | 3 +++
>   include/uapi/linux/iommu.h  | 3 ++-
>   2 files changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
> index 0b7e0e726ade..b7e39239f539 100644
> --- a/drivers/iommu/intel/pasid.c
> +++ b/drivers/iommu/intel/pasid.c
> @@ -763,6 +763,9 @@ intel_pasid_setup_bind_data(struct intel_iommu *iommu, struct pasid_entry *pte,
>   			return -EINVAL;
>   		}
>   		pasid_set_sre(pte);
> +		/* Enable write protect WP if guest requested */
> +		if (pasid_data->flags & IOMMU_SVA_VTD_GPASID_WPE)
> +			pasid_set_wpe(pte);
>   	}
>   
>   	if (pasid_data->flags & IOMMU_SVA_VTD_GPASID_EAFE) {
> diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> index 35d48843acd8..3a9164cc9937 100644
> --- a/include/uapi/linux/iommu.h
> +++ b/include/uapi/linux/iommu.h
> @@ -288,7 +288,8 @@ struct iommu_gpasid_bind_data_vtd {
>   #define IOMMU_SVA_VTD_GPASID_PWT	(1 << 3) /* page-level write through */
>   #define IOMMU_SVA_VTD_GPASID_EMTE	(1 << 4) /* extended mem type enable */
>   #define IOMMU_SVA_VTD_GPASID_CD		(1 << 5) /* PASID-level cache disable */
> -#define IOMMU_SVA_VTD_GPASID_LAST	(1 << 6)
> +#define IOMMU_SVA_VTD_GPASID_WPE	(1 << 6) /* Write protect enable */
> +#define IOMMU_SVA_VTD_GPASID_LAST	(1 << 7)
>   	__u64 flags;
>   	__u32 pat;
>   	__u32 emt;
> 

Acked-by: Lu Baolu <baolu.lu@...ux.intel.com>

Best regards,
baolu