Re: [PATCH v2 12/19] intel_iommu: Introduce a new pasid cache invalidation type FORCE_RESET

[Eric Auger <eric.auger@redhat.com>]

Hi Zhenzhong,

On 6/20/25 9:18 AM, Zhenzhong Duan wrote:
> FORCE_RESET is different from GLOBAL_INV which updates pasid cache if
> underlying pasid entry is still valid, it drops all the pasid caches.
>
> FORCE_RESET isn't a VTD spec defined invalidation type for pasid cache,
> only used internally in system level reset.
this comment shall be put in the code, along with the VTDPCInvType
because the reader may look for that cmd in the spec.
>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
> ---
>  hw/i386/intel_iommu_internal.h |  2 ++
>  hw/i386/intel_iommu.c          | 28 ++++++++++++++++++++++++++++
>  hw/i386/trace-events           |  1 +
>  3 files changed, 31 insertions(+)
>
> diff --git a/hw/i386/intel_iommu_internal.h b/hw/i386/intel_iommu_internal.h
> index 025787b3b9..5ed76864be 100644
> --- a/hw/i386/intel_iommu_internal.h
> +++ b/hw/i386/intel_iommu_internal.h
> @@ -564,6 +564,8 @@ typedef struct VTDRootEntry VTDRootEntry;
>  #define VTD_SM_CONTEXT_ENTRY_RSVD_VAL1      0xffffffffffe00000ULL
>  
>  typedef enum VTDPCInvType {
> +    /* Force reset all */
> +    VTD_PASID_CACHE_FORCE_RESET = 0,
>      /* pasid cache invalidation rely on guest PASID entry */
>      VTD_PASID_CACHE_GLOBAL_INV, /* pasid cache global invalidation */
>      VTD_PASID_CACHE_DOMSI,      /* pasid cache domain selective invalidation */
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index f4273dc640..ed71bb8ec7 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -87,6 +87,8 @@ struct vtd_iotlb_key {
>  static void vtd_address_space_refresh_all(IntelIOMMUState *s);
>  static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n);
>  
> +static void vtd_pasid_cache_reset_locked(IntelIOMMUState *s);
> +
>  static void vtd_panic_require_caching_mode(void)
>  {
>      error_report("We need to set caching-mode=on for intel-iommu to enable "
> @@ -391,6 +393,7 @@ static void vtd_reset_caches(IntelIOMMUState *s)
>      vtd_iommu_lock(s);
>      vtd_reset_iotlb_locked(s);
>      vtd_reset_context_cache_locked(s);
> +    vtd_pasid_cache_reset_locked(s);
>      vtd_iommu_unlock(s);
>  }
>  
> @@ -3196,6 +3199,8 @@ static gboolean vtd_flush_pasid(gpointer key, gpointer value,
>      }
>  
>      switch (pc_info->type) {
> +    case VTD_PASID_CACHE_FORCE_RESET:
> +        goto remove;
>      case VTD_PASID_CACHE_PASIDSI:
>          if (pc_info->pasid != pasid) {
>              return false;
> @@ -3251,6 +3256,26 @@ remove:
>      return true;
>  }
>  
> +/* Caller of this function should hold iommu_lock */
> +static void vtd_pasid_cache_reset_locked(IntelIOMMUState *s)
> +{
> +    VTDPASIDCacheInfo pc_info = {};
> +
> +    trace_vtd_pasid_cache_reset();
> +
> +    pc_info.type = VTD_PASID_CACHE_FORCE_RESET;
> +
> +    /*
> +     * Reset pasid cache is a big hammer, so use g_hash_table_foreach_remove
> +     * which will free the vtd_as instances. Also, as a big hammer, use
> +     * VTD_PASID_CACHE_FORCE_RESET to ensure all the vtd_as instances are
> +     * dropped, meanwhile the change will be passed to host if
> +     * HostIOMMUDeviceIOMMUFD is available.
> +     */
> +    g_hash_table_foreach_remove(s->vtd_address_spaces,
> +                                vtd_flush_pasid, &pc_info);
> +}
> +
>  static void vtd_sm_pasid_table_walk_one(IntelIOMMUState *s,
>                                          dma_addr_t pt_base,
>                                          int start,
> @@ -3377,6 +3402,9 @@ static void vtd_replay_guest_pasid_bindings(IntelIOMMUState *s,
>      case VTD_PASID_CACHE_GLOBAL_INV:
>          /* loop all assigned devices */
>          break;
> +    case VTD_PASID_CACHE_FORCE_RESET:
> +        /* For force reset, no need to go further replay */
> +        return;
>      default:
>          error_report("invalid pc_info->type for replay");
>          abort();
> diff --git a/hw/i386/trace-events b/hw/i386/trace-events
> index ae5bbfcdc0..c8a936eb46 100644
> --- a/hw/i386/trace-events
> +++ b/hw/i386/trace-events
> @@ -24,6 +24,7 @@ vtd_inv_qi_head(uint16_t head) "read head %d"
>  vtd_inv_qi_tail(uint16_t head) "write tail %d"
>  vtd_inv_qi_fetch(void) ""
>  vtd_context_cache_reset(void) ""
> +vtd_pasid_cache_reset(void) ""
>  vtd_pasid_cache_gsi(void) ""
>  vtd_pasid_cache_dsi(uint16_t domain) "Domain selective PC invalidation domain 0x%"PRIx16
>  vtd_pasid_cache_psi(uint16_t domain, uint32_t pasid) "PASID selective PC invalidation domain 0x%"PRIx16" pasid 0x%"PRIx32
Eric