Re: [PATCH v1 20/22] intel_iommu: propagate PASID-based iotlb invalidation to host

Peter Xu
2020-03-24T18:34:34Z

On Sun, Mar 22, 2020 at 05:36:17AM -0700, Liu Yi L wrote:
> This patch propagates PASID-based iotlb invalidation to host.
>
> Intel VT-d 3.0 supports nested translation in PASID granular.
> Guest SVA support could be implemented by configuring nested
> translation on specific PASID. This is also known as dual stage
> DMA translation.
>
> Under such configuration, guest owns the GVA->GPA translation
> which is configured as first level page table in host side for
> a specific pasid, and host owns GPA->HPA translation. As guest
> owns first level translation table, piotlb invalidation should
> be propagated to host since host IOMMU will cache first level
> page table related mappings during DMA address translation.
>
> This patch traps the guest PASID-based iotlb flush and propagate
> it to host.
>
> Cc: Kevin Tian <kevin.tian@intel.com>
> Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Cc: Peter Xu <peterx@redhat.com>
> Cc: Yi Sun <yi.y.sun@linux.intel.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Richard Henderson <rth@twiddle.net>
> Cc: Eduardo Habkost <ehabkost@redhat.com>
> Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> ---
> hw/i386/intel_iommu.c | 139 +++++++++++++++++++++++++++++++++++++++++
> hw/i386/intel_iommu_internal.h | 7 +++
> 2 files changed, 146 insertions(+)
>
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index b9ac07d..10d314d 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -3134,15 +3134,154 @@ static bool vtd_process_pasid_desc(IntelIOMMUState *s,
> return (ret == 0) ? true : false;
> }
>
> +/**
> + * Caller of this function should hold iommu_lock.
> + */
> +static void vtd_invalidate_piotlb(IntelIOMMUState *s,
> + VTDBus *vtd_bus,
> + int devfn,
> + DualIOMMUStage1Cache *stage1_cache)
> +{
> + VTDHostIOMMUContext *vtd_dev_icx;
> + HostIOMMUContext *host_icx;
> +
> + vtd_dev_icx = vtd_bus->dev_icx[devfn];
> + if (!vtd_dev_icx) {
> + goto out;
> + }
> + host_icx = vtd_dev_icx->host_icx;
> + if (!host_icx) {
> + goto out;
> + }
> + if (host_iommu_ctx_flush_stage1_cache(host_icx, stage1_cache)) {
> + error_report("Cache flush failed");

I think this should not easily be triggered by the guest, but just in
case... Let's use error_report_once() to be safe.

> + }
> +out:
> + return;
> +}
> +
> +static inline bool vtd_pasid_cache_valid(
> + VTDPASIDAddressSpace *vtd_pasid_as)
> +{
> + return vtd_pasid_as->iommu_state &&

This check can be dropped because always true?

If you agree with both the changes, please add:

Reviewed-by: Peter Xu <peterx@redhat.com>

> + (vtd_pasid_as->iommu_state->pasid_cache_gen
> + == vtd_pasid_as->pasid_cache_entry.pasid_cache_gen);
> +}
> +
> +/**
> + * This function is a loop function for the s->vtd_pasid_as
> + * list with VTDPIOTLBInvInfo as execution filter. It propagates
> + * the piotlb invalidation to host. Caller of this function
> + * should hold iommu_lock.
> + */
> +static void vtd_flush_pasid_iotlb(gpointer key, gpointer value,
> + gpointer user_data)
> +{
> + VTDPIOTLBInvInfo *piotlb_info = user_data;
> + VTDPASIDAddressSpace *vtd_pasid_as = value;
> + uint16_t did;
> +
> + /*
> + * Needs to check whether the pasid entry cache stored in
> + * vtd_pasid_as is valid or not. "invalid" means the pasid
> + * cache has been flushed, thus host should have done piotlb
> + * invalidation together with a pasid cache invalidation, so
> + * no need to pass down piotlb invalidation to host for better
> + * performance. Only when pasid entry cache is "valid", should
> + * a piotlb invalidation be propagated to host since it means
> + * guest just modified a mapping in its page table.
> + */
> + if (!vtd_pasid_cache_valid(vtd_pasid_as)) {
> + return;
> + }
> +
> + did = vtd_pe_get_domain_id(
> + &(vtd_pasid_as->pasid_cache_entry.pasid_entry));
> +
> + if ((piotlb_info->domain_id == did) &&
> + (piotlb_info->pasid == vtd_pasid_as->pasid)) {
> + vtd_invalidate_piotlb(vtd_pasid_as->iommu_state,
> + vtd_pasid_as->vtd_bus,
> + vtd_pasid_as->devfn,
> + piotlb_info->stage1_cache);
> + }
> +
> + /*
> + * TODO: needs to add QEMU piotlb flush when QEMU piotlb
> + * infrastructure is ready. For now, it is enough for passthru
> + * devices.
> + */
> +}
> +
> static void vtd_piotlb_pasid_invalidate(IntelIOMMUState *s,
> uint16_t domain_id,
> uint32_t pasid)
> {
> + VTDPIOTLBInvInfo piotlb_info;
> + DualIOMMUStage1Cache *stage1_cache;
> + struct iommu_cache_invalidate_info *cache_info;
> +
> + stage1_cache = g_malloc0(sizeof(*stage1_cache));
> + stage1_cache->pasid = pasid;
> +
> + cache_info = &stage1_cache->cache_info;
> + cache_info->version = IOMMU_UAPI_VERSION;
> + cache_info->cache = IOMMU_CACHE_INV_TYPE_IOTLB;
> + cache_info->granularity = IOMMU_INV_GRANU_PASID;
> + cache_info->pasid_info.pasid = pasid;
> + cache_info->pasid_info.flags = IOMMU_INV_PASID_FLAGS_PASID;
> +
> + piotlb_info.domain_id = domain_id;
> + piotlb_info.pasid = pasid;
> + piotlb_info.stage1_cache = stage1_cache;
> +
> + vtd_iommu_lock(s);
> + /*
> + * Here loops all the vtd_pasid_as instances in s->vtd_pasid_as
> + * to find out the affected devices since piotlb invalidation
> + * should check pasid cache per architecture point of view.
> + */
> + g_hash_table_foreach(s->vtd_pasid_as,
> + vtd_flush_pasid_iotlb, &piotlb_info);
> + vtd_iommu_unlock(s);
> + g_free(stage1_cache);
> }
>
> static void vtd_piotlb_page_invalidate(IntelIOMMUState *s, uint16_t domain_id,
> uint32_t pasid, hwaddr addr, uint8_t am, bool ih)
> {
> + VTDPIOTLBInvInfo piotlb_info;
> + DualIOMMUStage1Cache *stage1_cache;
> + struct iommu_cache_invalidate_info *cache_info;
> +
> + stage1_cache = g_malloc0(sizeof(*stage1_cache));
> + stage1_cache->pasid = pasid;
> +
> + cache_info = &stage1_cache->cache_info;
> + cache_info->version = IOMMU_UAPI_VERSION;
> + cache_info->cache = IOMMU_CACHE_INV_TYPE_IOTLB;
> + cache_info->granularity = IOMMU_INV_GRANU_ADDR;
> + cache_info->addr_info.flags = IOMMU_INV_ADDR_FLAGS_PASID;
> + cache_info->addr_info.flags |= ih ? IOMMU_INV_ADDR_FLAGS_LEAF : 0;
> + cache_info->addr_info.pasid = pasid;
> + cache_info->addr_info.addr = addr;
> + cache_info->addr_info.granule_size = 1 << (12 + am);
> + cache_info->addr_info.nb_granules = 1;
> +
> + piotlb_info.domain_id = domain_id;
> + piotlb_info.pasid = pasid;
> + piotlb_info.stage1_cache = stage1_cache;
> +
> + vtd_iommu_lock(s);
> + /*
> + * Here loops all the vtd_pasid_as instances in s->vtd_pasid_as
> + * to find out the affected devices since piotlb invalidation
> + * should check pasid cache per architecture point of view.
> + */
> + g_hash_table_foreach(s->vtd_pasid_as,
> + vtd_flush_pasid_iotlb, &piotlb_info);
> + vtd_iommu_unlock(s);
> + g_free(stage1_cache);
> }
>
> static bool vtd_process_piotlb_desc(IntelIOMMUState *s,
> diff --git a/hw/i386/intel_iommu_internal.h b/hw/i386/intel_iommu_internal.h
> index 314e2c4..967cc4f 100644
> --- a/hw/i386/intel_iommu_internal.h
> +++ b/hw/i386/intel_iommu_internal.h
> @@ -560,6 +560,13 @@ struct VTDPASIDCacheInfo {
> VTD_PASID_CACHE_DEVSI)
> typedef struct VTDPASIDCacheInfo VTDPASIDCacheInfo;
>
> +struct VTDPIOTLBInvInfo {
> + uint16_t domain_id;
> + uint32_t pasid;
> + DualIOMMUStage1Cache *stage1_cache;
> +};
> +typedef struct VTDPIOTLBInvInfo VTDPIOTLBInvInfo;
> +
> /* PASID Table Related Definitions */
> #define VTD_PASID_DIR_BASE_ADDR_MASK (~0xfffULL)
> #define VTD_PASID_TABLE_BASE_ADDR_MASK (~0xfffULL)
> --
> 2.7.4
>

--
Peter Xu