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Message-ID: <20191023004503.GB100970@otc-nc-03>
Date: Tue, 22 Oct 2019 17:45:03 -0700
From: "Raj, Ashok" <ashok.raj@...el.com>
To: Jacob Pan <jacob.jun.pan@...ux.intel.com>
Cc: iommu@...ts.linux-foundation.org,
LKML <linux-kernel@...r.kernel.org>,
Joerg Roedel <joro@...tes.org>,
David Woodhouse <dwmw2@...radead.org>,
Alex Williamson <alex.williamson@...hat.com>,
Jean-Philippe Brucker <jean-philippe@...aro.com>,
Yi Liu <yi.l.liu@...el.com>,
"Tian, Kevin" <kevin.tian@...el.com>,
Christoph Hellwig <hch@...radead.org>,
Lu Baolu <baolu.lu@...ux.intel.com>,
Jonathan Cameron <jic23@...nel.org>,
Eric Auger <eric.auger@...hat.com>,
Ashok Raj <ashok.raj@...el.com>
Subject: Re: [PATCH v6 01/10] iommu/vt-d: Enlightened PASID allocation
On Tue, Oct 22, 2019 at 04:53:14PM -0700, Jacob Pan wrote:
> From: Lu Baolu <baolu.lu@...ux.intel.com>
>
> If Intel IOMMU runs in caching mode, a.k.a. virtual IOMMU, the
> IOMMU driver should rely on the emulation software to allocate
> and free PASID IDs. The Intel vt-d spec revision 3.0 defines a
> register set to support this. This includes 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.
The above paragraph seems a bit confusing, there is no reference
to caching mode for for VCMD... some suggestion below.
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 and
proxies the call to the host driver....
>
> This patch adds the enlightened PASID allocation/free interfaces
> via the virtual command register.
>
> Cc: Ashok Raj <ashok.raj@...el.com>
> Cc: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> Cc: Kevin Tian <kevin.tian@...el.com>
> Signed-off-by: Liu Yi L <yi.l.liu@...el.com>
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> Reviewed-by: Eric Auger <eric.auger@...hat.com>
> ---
> drivers/iommu/intel-pasid.c | 83 +++++++++++++++++++++++++++++++++++++++++++++
> drivers/iommu/intel-pasid.h | 13 ++++++-
> include/linux/intel-iommu.h | 2 ++
> 3 files changed, 97 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
> index 040a445be300..76bcbb21e112 100644
> --- a/drivers/iommu/intel-pasid.c
> +++ b/drivers/iommu/intel-pasid.c
> @@ -63,6 +63,89 @@ void *intel_pasid_lookup_id(int pasid)
> return p;
> }
>
> +static int check_vcmd_pasid(struct intel_iommu *iommu)
> +{
> + u64 cap;
> +
> + if (!ecap_vcs(iommu->ecap)) {
> + pr_warn("IOMMU: %s: Hardware doesn't support virtual command\n",
> + iommu->name);
> + return -ENODEV;
> + }
> +
> + cap = dmar_readq(iommu->reg + DMAR_VCCAP_REG);
> + if (!(cap & DMA_VCS_PAS)) {
> + pr_warn("IOMMU: %s: Emulation software doesn't support PASID allocation\n",
> + iommu->name);
> + return -ENODEV;
> + }
> +
> + return 0;
> +}
> +
> +int vcmd_alloc_pasid(struct intel_iommu *iommu, unsigned int *pasid)
> +{
> + u64 res;
> + u8 status_code;
> + unsigned long flags;
> + int ret = 0;
> +
> + ret = check_vcmd_pasid(iommu);
Do you have to check this everytime? every dmar_readq is going to trap
to the other side ...
> + if (ret)
> + return ret;
> +
> + 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)
> +{
> + u64 res;
> + u8 status_code;
> + unsigned long flags;
> +
> + if (check_vcmd_pasid(iommu))
> + return;
> +
> + 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)
> +
> /*
> * 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 ed11ef594378..eea7468694a7 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)
> @@ -279,6 +280,7 @@
>
> /* 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
>
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