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

[Jacob Pan]

On Fri, 8 Nov 2019 11:33:22 +0100
Auger Eric <eric.auger@xxxxxxxxxx> wrote:

> Hi Jacob,
> On 10/24/19 9:54 PM, Jacob Pan wrote:
> > From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > 
> > 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@xxxxxxxxx>
> > Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> > Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
> > Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx>
> > Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> > Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx>
> > ---
> >  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);
> > +
> > +	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);
> > +	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)  
> nit: pasid is 20b but result field is 56b large
> Just in case a new command were to be added later on.
Good point, will rename to VCMD_VRSP_RESULT_PASID andd new macros for
future new commands with different results.
> > +
> >  /*
> >   * 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)  
> nit: this addition is not related to this patch
> may be moved to [3] as vccap_pasid
Sounds good.

Thanks
> >  #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
> > {
> > \ 
> Otherwise looks good to me
> 
> Thanks
> 
> Eric
> 

[Jacob Pan]