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

From: Lu Baolu <baolu.lu@linux.intel.com>
To: Jacob Pan <jacob.jun.pan@linux.intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	iommu@lists.linux-foundation.org, Joerg Roedel <joro@8bytes.org>,
	David Woodhouse <dwmw2@infradead.org>
Cc: baolu.lu@linux.intel.com, Yi Liu <yi.l.liu@intel.com>,
	Raj Ashok <ashok.raj@intel.com>,
	"Tian, Kevin" <kevin.tian@intel.com>,
	Eric Auger <eric.auger@redhat.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.com>,
	Sanjay Kumar <sanjay.k.kumar@intel.com>
Subject: Re: [PATCH v2 2/4] iommu/vt-d: Enable write protect propagation from guest
Date: Wed, 3 Mar 2021 12:57:17 +0800	[thread overview]
Message-ID: <ed71158c-d906-f503-3372-dd7936a992ba@linux.intel.com> (raw)
In-Reply-To: <1614680040-1989-3-git-send-email-jacob.jun.pan@linux.intel.com>

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@intel.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.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@linux.intel.com>

Best regards,
baolu