Re: [PATCH V10 10/11] iommu/vt-d: Enlightened PASID allocation

[Jacob Pan <jacob.jun.pan@linux.intel.com>]

On Sat, 28 Mar 2020 10:08:52 +0000
"Tian, Kevin" <kevin.tian@intel.com> wrote:

> > From: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > Sent: Saturday, March 21, 2020 7:28 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.  
> 
> Qemu -> vIOMMU
> 
Sounds good. Thanks!
> > 
> > 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 | 57
> > +++++++++++++++++++++++++++++++++++++++++++++
> >  drivers/iommu/intel-pasid.h | 13 ++++++++++-
> >  include/linux/intel-iommu.h |  1 +
> >  3 files changed, 70 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/iommu/intel-pasid.c
> > b/drivers/iommu/intel-pasid.c index 9f6d07410722..e87ad67aad36
> > 100644 --- a/drivers/iommu/intel-pasid.c
> > +++ b/drivers/iommu/intel-pasid.c
> > @@ -27,6 +27,63 @@
> >  static DEFINE_SPINLOCK(pasid_lock);
> >  u32 intel_pasid_max_id = PASID_MAX;
> > 
> > +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);
> > +
> > +	status_code = VCMD_VRSP_SC(res);
> > +	switch (status_code) {
> > +	case VCMD_VRSP_SC_SUCCESS:
> > +		*pasid = VCMD_VRSP_RESULT_PASID(res);
> > +		break;
> > +	case VCMD_VRSP_SC_NO_PASID_AVAIL:
> > +		pr_info("IOMMU: %s: No PASID available\n",
> > iommu->name);
> > +		ret = -ENOSPC;
> > +		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,
> > +		    VCMD_CMD_OPERAND(pasid) | VCMD_CMD_FREE);
> > +	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 698015ee3f04..cd3d63f3e936
> > 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_PASID(e)	(((e) >> 8) & 0xfffff)
> > +#define VCMD_CMD_OPERAND(e)		((e) << 8)
> >  /*
> >   * Domain ID reserved for pasid entries programmed for first-level
> >   * only and pass-through transfer modes.
> > @@ -113,5 +123,6 @@ int intel_pasid_setup_nested(struct intel_iommu
> > *iommu,
> >  			int addr_width);
> >  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 ccbf164fb711..9cbf5357138b
> > 100644 --- a/include/linux/intel-iommu.h
> > +++ b/include/linux/intel-iommu.h
> > @@ -169,6 +169,7 @@
> >  #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)
> > --
> > 2.7.4  
> 
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> 

[Jacob Pan]