RE: [PATCH v7 02/11] iommu/vt-d: Enlightened PASID allocation

From: "Tian, Kevin" <kevin.tian@intel.com>
To: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: "Raj, Ashok" <ashok.raj@intel.com>,
	David Woodhouse <dwmw2@infradead.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Alex Williamson <alex.williamson@redhat.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.com>,
	Jonathan Cameron <jic23@kernel.org>
Subject: RE: [PATCH v7 02/11] iommu/vt-d: Enlightened PASID allocation
Date: Tue, 29 Oct 2019 18:16:40 +0000
Message-ID: <AADFC41AFE54684AB9EE6CBC0274A5D19D5DEE2B@SHSMSX104.ccr.corp.intel.com> (raw)
In-Reply-To: <20191029101436.3ca8d438@jacob-builder>

> From: Jacob Pan [mailto:jacob.jun.pan@linux.intel.com]
> Sent: Wednesday, October 30, 2019 1:15 AM
> > >
> > > From: Lu Baolu <baolu.lu@linux.intel.com>
> > >
> > > Enabling IOMMU in a guest requires communication with the host
> > > driver for certain aspects. Use of PASID ID to enable Shared Virtual
> > > Addressing (SVA) requires managing PASID's in the host. VT-d 3.0
> > > spec provides a Virtual Command Register (VCMD) to facilitate this.
> > > Writes to this register in the guest are trapped by QEMU which
> > > proxies the call to the host driver.
> > >
> > > This virtual command interface consists of a capability register,
> > > a virtual command register, and a virtual response register. Refer
> > > to section 10.4.42, 10.4.43, 10.4.44 for more information.
> > >
> > > This patch adds the enlightened PASID allocation/free interfaces
> > > via the virtual command interface.
> > >
> > > Cc: Ashok Raj <ashok.raj@intel.com>
> > > Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > > Cc: Kevin Tian <kevin.tian@intel.com>
> > > Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> > > Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> > > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > > Reviewed-by: Eric Auger <eric.auger@redhat.com>
> > > ---
> > >  drivers/iommu/intel-pasid.c | 56
> > > +++++++++++++++++++++++++++++++++++++++++++++
> > >  drivers/iommu/intel-pasid.h | 13 ++++++++++-
> > >  include/linux/intel-iommu.h |  2 ++
> > >  3 files changed, 70 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/iommu/intel-pasid.c
> > > b/drivers/iommu/intel-pasid.c index 040a445be300..d81e857d2b25
> > > 100644 --- a/drivers/iommu/intel-pasid.c
> > > +++ b/drivers/iommu/intel-pasid.c
> > > @@ -63,6 +63,62 @@ void *intel_pasid_lookup_id(int pasid)
> > >  	return p;
> > >  }
> > >
> > > +int vcmd_alloc_pasid(struct intel_iommu *iommu, unsigned int
> > > *pasid) +{
> > > +	unsigned long flags;
> > > +	u8 status_code;
> > > +	int ret = 0;
> > > +	u64 res;
> > > +
> > > +	raw_spin_lock_irqsave(&iommu->register_lock, flags);
> > > +	dmar_writeq(iommu->reg + DMAR_VCMD_REG,
> > > VCMD_CMD_ALLOC);
> > > +	IOMMU_WAIT_OP(iommu, DMAR_VCRSP_REG, dmar_readq,
> > > +		      !(res & VCMD_VRSP_IP), res);
> > > +	raw_spin_unlock_irqrestore(&iommu->register_lock, flags);
> > > +
> >
> > should we handle VCMD_VRSP_IP here?
> VCMD_VRSP_IP is checked above, if it times out, you will get panic. Not
> sure whatelse to do?

Not need. I misunderstood the condition here.

> >
> > > +	status_code = VCMD_VRSP_SC(res);
> > > +	switch (status_code) {
> > > +	case VCMD_VRSP_SC_SUCCESS:
> > > +		*pasid = VCMD_VRSP_RESULT(res);
> > > +		break;
> > > +	case VCMD_VRSP_SC_NO_PASID_AVAIL:
> > > +		pr_info("IOMMU: %s: No PASID available\n", iommu-
> > > >name);
> > > +		ret = -ENOMEM;
> > > +		break;
> > > +	default:
> > > +		ret = -ENODEV;
> > > +		pr_warn("IOMMU: %s: Unexpected error code %d\n",
> > > +			iommu->name, status_code);
> > > +	}
> > > +
> > > +	return ret;
> > > +}
> > > +
> > > +void vcmd_free_pasid(struct intel_iommu *iommu, unsigned int pasid)
> > > +{
> > > +	unsigned long flags;
> > > +	u8 status_code;
> > > +	u64 res;
> > > +
> > > +	raw_spin_lock_irqsave(&iommu->register_lock, flags);
> > > +	dmar_writeq(iommu->reg + DMAR_VCMD_REG, (pasid << 8) |
> > > VCMD_CMD_FREE);
> >
> > define a macro for pasid offset.
> >
> will do.
> 
> > > +	IOMMU_WAIT_OP(iommu, DMAR_VCRSP_REG, dmar_readq,
> > > +		      !(res & VCMD_VRSP_IP), res);
> > > +	raw_spin_unlock_irqrestore(&iommu->register_lock, flags);
> > > +
> > > +	status_code = VCMD_VRSP_SC(res);
> > > +	switch (status_code) {
> > > +	case VCMD_VRSP_SC_SUCCESS:
> > > +		break;
> > > +	case VCMD_VRSP_SC_INVALID_PASID:
> > > +		pr_info("IOMMU: %s: Invalid PASID\n", iommu->name);
> > > +		break;
> > > +	default:
> > > +		pr_warn("IOMMU: %s: Unexpected error code %d\n",
> > > +			iommu->name, status_code);
> > > +	}
> > > +}
> > > +
> > >  /*
> > >   * Per device pasid table management:
> > >   */
> > > diff --git a/drivers/iommu/intel-pasid.h
> > > b/drivers/iommu/intel-pasid.h index fc8cd8f17de1..e413e884e685
> > > 100644 --- a/drivers/iommu/intel-pasid.h
> > > +++ b/drivers/iommu/intel-pasid.h
> > > @@ -23,6 +23,16 @@
> > >  #define is_pasid_enabled(entry)		(((entry)->lo >> 3)
> > > & 0x1) #define get_pasid_dir_size(entry)	(1 <<
> > > ((((entry)->lo >> 9) & 0x7) + 7))
> > >
> > > +/* Virtual command interface for enlightened pasid management. */
> > > +#define VCMD_CMD_ALLOC			0x1
> > > +#define VCMD_CMD_FREE			0x2
> > > +#define VCMD_VRSP_IP			0x1
> > > +#define VCMD_VRSP_SC(e)			(((e) >> 1) & 0x3)
> > > +#define VCMD_VRSP_SC_SUCCESS		0
> > > +#define VCMD_VRSP_SC_NO_PASID_AVAIL	1
> > > +#define VCMD_VRSP_SC_INVALID_PASID	1
> > > +#define VCMD_VRSP_RESULT(e)		(((e) >> 8) & 0xfffff)
> > > +
> > >  /*
> > >   * Domain ID reserved for pasid entries programmed for first-level
> > >   * only and pass-through transfer modes.
> > > @@ -95,5 +105,6 @@ int intel_pasid_setup_pass_through(struct
> > > intel_iommu *iommu,
> > >  				   struct device *dev, int pasid);
> > >  void intel_pasid_tear_down_entry(struct intel_iommu *iommu,
> > >  				 struct device *dev, int pasid);
> > > -
> > > +int vcmd_alloc_pasid(struct intel_iommu *iommu, unsigned int
> > > *pasid); +void vcmd_free_pasid(struct intel_iommu *iommu, unsigned
> > > int pasid); #endif /* __INTEL_PASID_H */
> > > diff --git a/include/linux/intel-iommu.h
> > > b/include/linux/intel-iommu.h index 2e1bed9b7eef..1d4b8dcdc5d8
> > > 100644 --- a/include/linux/intel-iommu.h
> > > +++ b/include/linux/intel-iommu.h
> > > @@ -161,6 +161,7 @@
> > >  #define ecap_smpwc(e)		(((e) >> 48) & 0x1)
> > >  #define ecap_flts(e)		(((e) >> 47) & 0x1)
> > >  #define ecap_slts(e)		(((e) >> 46) & 0x1)
> > > +#define ecap_vcs(e)		(((e) >> 44) & 0x1)
> > >  #define ecap_smts(e)		(((e) >> 43) & 0x1)
> > >  #define ecap_dit(e)		((e >> 41) & 0x1)
> > >  #define ecap_pasid(e)		((e >> 40) & 0x1)
> > > @@ -282,6 +283,7 @@
> > >
> > >  /* PRS_REG */
> > >  #define DMA_PRS_PPR	((u32)1)
> > > +#define DMA_VCS_PAS	((u64)1)
> > >
> > >  #define IOMMU_WAIT_OP(iommu, offset, op, cond, sts)
> > > 	\
> > >  do
> > > {
> > > \ -- 2.7.4
> >
> 
> [Jacob Pan]
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