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

[Tian, Kevin]

> From: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> Sent: Saturday, March 21, 2020 7:28 AM
> 
> 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.

Qemu -> vIOMMU

> 
> 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 | 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@xxxxxxxxx>