Re: [PATCH 3/7] iommu/vt-d: Support Enhanced Command Interface

[Baolu Lu <baolu.lu@linux.intel.com>]

On 2023/1/12 4:25, kan.liang@linux.intel.com wrote:
> From: Kan Liang <kan.liang@linux.intel.com>
> 
> The Enhanced Command Register is to submit command and operand of
> enhanced commands to DMA Remapping hardware. It can supports upto 256
> enhanced commands.
> 
> There is a HW register to indicate the availability of all 256 enhanced
> commands. Each bit stands for each command. But there isn't an existing
> interface to read/write all 256 bits. Introduce the u64 ecmdcap[4] to
> store the existence of each enhanced command. Read 4 times to get
> all of them in map_iommu().
> 
> Add a helper to facilitate an enhanced command launch. Make sure hardware
> complete the command.
> 
> Add a helper to facilitate the check of PMU essentials.
> 
> The helpers will be used later.
> 
> Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
> ---
>   drivers/iommu/intel/dmar.c  | 63 +++++++++++++++++++++++++++++++++++++
>   drivers/iommu/intel/iommu.h | 46 +++++++++++++++++++++++++++
>   2 files changed, 109 insertions(+)
> 
> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
> index 91bb48267df2..dcafa32875c1 100644
> --- a/drivers/iommu/intel/dmar.c
> +++ b/drivers/iommu/intel/dmar.c
> @@ -1025,6 +1025,16 @@ static int map_iommu(struct intel_iommu *iommu, struct dmar_drhd_unit *drhd)
>   			goto release;
>   		}
>   	}
> +
> +	if (cap_ecmds(iommu->cap)) {
> +		int i;
> +
> +		for (i = 0; i < DMA_MAX_NUM_ECMDCAP; i++) {
> +			iommu->ecmdcap[i] = dmar_readq(iommu->reg + DMAR_ECCAP_REG +
> +						       i * DMA_ECMD_REG_STEP);
> +		}
> +	}
> +
>   	err = 0;
>   	goto out;
>   
> @@ -2434,3 +2444,56 @@ bool dmar_platform_optin(void)
>   	return ret;
>   }
>   EXPORT_SYMBOL_GPL(dmar_platform_optin);
> +
> +#ifdef CONFIG_INTEL_IOMMU

Why do you need above #ifdef?

> +#define ecmd_get_status_code(res)	((res & 0xff) >> 1)
> +
> +/*
> + * Function to submit a command to the enhanced command interface. The
> + * valid enhanced command descriptions are defined in Table 47 of the
> + * VT-d spec. The VT-d hardware implementation may support some but not
> + * all commands, which can be determined by checking the Enhanced
> + * Command Capability Register.
> + *
> + * Return values:
> + *  - 0: Command successful without any error;
> + *  - Negative: software error value;
> + *  - Nonzero positive: failure status code defined in Table 48.
> + */
> +int ecmd_submit_sync(struct intel_iommu *iommu, u8 ecmd,
> +		     u64 oa, bool has_ob, u64 ob)
> +{
> +	unsigned long flags;
> +	u64 res;
> +	int ret;
> +
> +	if (!cap_ecmds(iommu->cap))
> +		return -ENODEV;
> +
> +	raw_spin_lock_irqsave(&iommu->register_lock, flags);
> +
> +	res = dmar_readq(iommu->reg + DMAR_ECRSP_REG);
> +	if (res & DMA_ECMD_ECRSP_IP) {
> +		ret = -EBUSY;
> +		goto err;
> +	}
> +
> +	if (has_ob)
> +		dmar_writeq(iommu->reg + DMAR_ECEO_REG, ob);

The ecmds that require a Operand B are statically defined in the spec,
right? What will it look like if we define a static ignore_ob(ecmd)?

> +	dmar_writeq(iommu->reg + DMAR_ECMD_REG, ecmd | (oa << DMA_ECMD_OA_SHIFT));
> +
> +	IOMMU_WAIT_OP(iommu, DMAR_ECRSP_REG, dmar_readq,
> +		      !(res & DMA_ECMD_ECRSP_IP), res);
> +
> +	if (res & DMA_ECMD_ECRSP_IP) {
> +		ret = -ETIMEDOUT;
> +		goto err;
> +	}
> +
> +	ret = ecmd_get_status_code(res);
> +err:
> +	raw_spin_unlock_irqrestore(&iommu->register_lock, flags);
> +
> +	return ret;
> +}
> +#endif /* CONFIG_INTEL_IOMMU */
> diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
> index 5bcefbea55c9..f227107434ac 100644
> --- a/drivers/iommu/intel/iommu.h
> +++ b/drivers/iommu/intel/iommu.h
> @@ -130,6 +130,10 @@
>   #define DMAR_PERFOVFOFF_REG	0x318
>   #define DMAR_PERFCNTROFF_REG	0x31c
>   #define DMAR_PERFEVNTCAP_REG	0x380
> +#define DMAR_ECMD_REG		0x400
> +#define DMAR_ECEO_REG		0x408
> +#define DMAR_ECRSP_REG		0x410
> +#define DMAR_ECCAP_REG		0x430
>   #define DMAR_VCCAP_REG		0xe30 /* Virtual command capability register */
>   #define DMAR_VCMD_REG		0xe00 /* Virtual command register */
>   #define DMAR_VCRSP_REG		0xe10 /* Virtual command response register */
> @@ -304,6 +308,26 @@
>   #define DMA_CCMD_SID(s) (((u64)((s) & 0xffff)) << 16)
>   #define DMA_CCMD_DID(d) ((u64)((d) & 0xffff))
>   
> +/* ECMD_REG */
> +#define DMA_MAX_NUM_ECMD		256
> +#define DMA_MAX_NUM_ECMDCAP		(DMA_MAX_NUM_ECMD / 64)
> +#define DMA_ECMD_REG_STEP		8
> +#define DMA_ECMD_ENABLE			0xf0
> +#define DMA_ECMD_DISABLE		0xf1
> +#define DMA_ECMD_FREEZE			0xf4
> +#define DMA_ECMD_UNFREEZE		0xf5
> +#define DMA_ECMD_OA_SHIFT		16
> +#define DMA_ECMD_ECRSP_IP		0x1
> +#define DMA_ECMD_ECCAP3			3
> +#define DMA_ECMD_ECCAP3_ECNTS		(1ULL << 48)
> +#define DMA_ECMD_ECCAP3_DCNTS		(1ULL << 49)
> +#define DMA_ECMD_ECCAP3_FCNTS		(1ULL << 52)
> +#define DMA_ECMD_ECCAP3_UFCNTS		(1ULL << 53)
> +#define DMA_ECMD_ECCAP3_ESSENTIAL	(DMA_ECMD_ECCAP3_ECNTS |	\
> +					 DMA_ECMD_ECCAP3_DCNTS |	\
> +					 DMA_ECMD_ECCAP3_FCNTS |	\
> +					 DMA_ECMD_ECCAP3_UFCNTS)
> +
>   /* FECTL_REG */
>   #define DMA_FECTL_IM (((u32)1) << 31)
>   
> @@ -600,6 +624,7 @@ struct intel_iommu {
>   	u64		cap;
>   	u64		ecap;
>   	u64		vccap;
> +	u64		ecmdcap[DMA_MAX_NUM_ECMDCAP];
>   	u32		gcmd; /* Holds TE, EAFL. Don't need SRTP, SFL, WBF */
>   	raw_spinlock_t	register_lock; /* protect register handling */
>   	int		seq_id;	/* sequence id of the iommu */
> @@ -841,6 +866,15 @@ extern const struct iommu_ops intel_iommu_ops;
>   extern int intel_iommu_sm;
>   extern int iommu_calculate_agaw(struct intel_iommu *iommu);
>   extern int iommu_calculate_max_sagaw(struct intel_iommu *iommu);
> +extern int ecmd_submit_sync(struct intel_iommu *iommu, u8 ecmd,
> +			    u64 oa, bool has_ob, u64 ob);
> +
> +static inline bool ecmd_has_pmu_essential(struct intel_iommu *iommu)
> +{
> +	return (iommu->ecmdcap[DMA_ECMD_ECCAP3] & DMA_ECMD_ECCAP3_ESSENTIAL) ==
> +		DMA_ECMD_ECCAP3_ESSENTIAL;
> +}
> +
>   extern int dmar_disabled;
>   extern int intel_iommu_enabled;
>   #else
> @@ -852,6 +886,18 @@ static inline int iommu_calculate_max_sagaw(struct intel_iommu *iommu)
>   {
>   	return 0;
>   }
> +
> +static inline int ecmd_submit_sync(struct intel_iommu *iommu, u8 ecmd,
> +				   u64 oa, bool has_ob, u64 ob)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static inline bool ecmd_has_pmu_essential(struct intel_iommu *iommu)
> +{
> +	return false;
> +}

Is there any need to call these helpers when INTEL_IOMMU is not
configured?

> +
>   #define dmar_disabled	(1)
>   #define intel_iommu_enabled (0)
>   #define intel_iommu_sm (0)

--
Best regards,
baolu