Messages in this thread Patch in this message | | | Date | Mon, 22 Feb 2021 10:01:06 -0800 | From | Jacob Pan <> | Subject | Re: [PATCH 2/4] iommu/vt-d: Enable write protect propagation from guest |
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Hi Kevin,
On Sat, 20 Feb 2021 02:38:02 +0000, "Tian, Kevin" <kevin.tian@intel.com> wrote:
> > From: Jacob Pan <jacob.jun.pan@linux.intel.com> > > Sent: Saturday, February 20, 2021 1:09 AM > > > > Hi Kevin, > > > > On Fri, 19 Feb 2021 06:19:04 +0000, "Tian, Kevin" <kevin.tian@intel.com> > > wrote: > > > > > > From: Jacob Pan <jacob.jun.pan@linux.intel.com> > > > > Sent: Friday, February 19, 2021 5:31 AM > > > > > > > > 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 | 5 +++++ > > > > include/uapi/linux/iommu.h | 3 ++- > > > > 2 files changed, 7 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/iommu/intel/pasid.c > > > > b/drivers/iommu/intel/pasid.c index 0b7e0e726ade..c7a2ec930af4 > > > > 100644 --- a/drivers/iommu/intel/pasid.c > > > > +++ b/drivers/iommu/intel/pasid.c > > > > @@ -763,6 +763,11 @@ 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) { > > > > + if (pasid_enable_wpe(pte)) > > > > + return -EINVAL; > > > > > > We should call pasid_set_wpe directly, as this binding is about guest > > > page table and suppose the guest has done whatever check required > > > (e.g. gcr0.wp) before setting this bit. pasid_enable_wpe has an > > > additional check on host cr0.wp thus is logically incorrect here. > > > > > If the host CPU does not support WP, can guest VCPU still support WP? If > > so, I agree. > > > > If you change 'support' to 'enable', then the answer is yes.
I agree, thanks for explaining. Will change it to pasid_set_wpe.
Thanks,
Jacob
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