[PATCH 0/3] virtio-iommu: Support VIRTIO_IOMMU_F_BYPASS_CONFIG

[PATCH 0/3] virtio-iommu: Support VIRTIO_IOMMU_F_BYPASS_CONFIG

[Jean-Philippe Brucker]

Replace the VIRTIO_IOMMU_F_BYPASS feature with
VIRTIO_IOMMU_F_BYPASS_CONFIG, which enables a config space bit to switch
global bypass on and off.

Add a boot-bypass option, which defaults to 'on' to be in line with
other vIOMMUs and to allow running firmware/bootloader that are unaware
of the IOMMU.

See the spec change for more rationale
https://lists.oasis-open.org/archives/virtio-dev/202109/msg00137.html

Jean-Philippe Brucker (3):
  NOMERGE: virtio-iommu: Add definitions for
    VIRTIO_IOMMU_F_BYPASS_CONFIG
  virtio-iommu: Default to bypass during boot
  virtio-iommu: Support bypass domain

 include/hw/virtio/virtio-iommu.h              |  1 +
 include/standard-headers/linux/virtio_iommu.h | 10 +++-
 hw/virtio/virtio-iommu.c                      | 60 ++++++++++++++++---
 hw/virtio/trace-events                        |  4 +-
 4 files changed, 64 insertions(+), 11 deletions(-)

-- 
2.33.0

[PATCH 1/3] NOMERGE: virtio-iommu: Add definitions for VIRTIO_IOMMU_F_BYPASS_CONFIG

[Jean-Philippe Brucker]

Pull VIRTIO_IOMMU_F_BYPASS_CONFIG changes from Linux (not upstream yet).

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 include/standard-headers/linux/virtio_iommu.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/standard-headers/linux/virtio_iommu.h b/include/standard-headers/linux/virtio_iommu.h
index b9443b83a1..d14808e3fb 100644
--- a/include/standard-headers/linux/virtio_iommu.h
+++ b/include/standard-headers/linux/virtio_iommu.h
@@ -13,9 +13,10 @@
 #define VIRTIO_IOMMU_F_INPUT_RANGE		0
 #define VIRTIO_IOMMU_F_DOMAIN_RANGE		1
 #define VIRTIO_IOMMU_F_MAP_UNMAP		2
-#define VIRTIO_IOMMU_F_BYPASS			3
+#define VIRTIO_IOMMU_F_BYPASS			3 /* Deprecated */
 #define VIRTIO_IOMMU_F_PROBE			4
 #define VIRTIO_IOMMU_F_MMIO			5
+#define VIRTIO_IOMMU_F_BYPASS_CONFIG		6
 
 struct virtio_iommu_range_64 {
 	uint64_t					start;
@@ -36,6 +37,8 @@ struct virtio_iommu_config {
 	struct virtio_iommu_range_32		domain_range;
 	/* Probe buffer size */
 	uint32_t					probe_size;
+	uint8_t					bypass;
+	uint8_t					reserved[7];
 };
 
 /* Request types */
@@ -66,11 +69,14 @@ struct virtio_iommu_req_tail {
 	uint8_t					reserved[3];
 };
 
+#define VIRTIO_IOMMU_ATTACH_F_BYPASS		(1 << 0)
+
 struct virtio_iommu_req_attach {
 	struct virtio_iommu_req_head		head;
 	uint32_t					domain;
 	uint32_t					endpoint;
-	uint8_t					reserved[8];
+	uint32_t					flags;
+	uint8_t					reserved[4];
 	struct virtio_iommu_req_tail		tail;
 };
 
-- 
2.33.0

[PATCH 2/3] virtio-iommu: Default to bypass during boot

[Jean-Philippe Brucker]

Currently the virtio-iommu device must be programmed before it allows
DMA from any PCI device. This can make the VM entirely unusable when a
virtio-iommu driver isn't present, for example in a bootloader that
loads the OS from storage.

Similarly to the other vIOMMU implementations, default to DMA bypassing
the IOMMU during boot. Add a "boot-bypass" option that lets users change
this behavior.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 include/hw/virtio/virtio-iommu.h |  1 +
 hw/virtio/virtio-iommu.c         | 28 +++++++++++++++++++++++-----
 hw/virtio/trace-events           |  4 ++--
 3 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/include/hw/virtio/virtio-iommu.h b/include/hw/virtio/virtio-iommu.h
index 273e35c04b..4c66989ca4 100644
--- a/include/hw/virtio/virtio-iommu.h
+++ b/include/hw/virtio/virtio-iommu.h
@@ -58,6 +58,7 @@ struct VirtIOIOMMU {
     GTree *domains;
     QemuMutex mutex;
     GTree *endpoints;
+    bool boot_bypass;
 };
 
 #endif
diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
index 1b23e8e18c..82edeaa101 100644
--- a/hw/virtio/virtio-iommu.c
+++ b/hw/virtio/virtio-iommu.c
@@ -728,8 +728,7 @@ static IOMMUTLBEntry virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
         .perm = IOMMU_NONE,
     };
 
-    bypass_allowed = virtio_vdev_has_feature(&s->parent_obj,
-                                             VIRTIO_IOMMU_F_BYPASS);
+    bypass_allowed = s->config.bypass;
 
     sid = virtio_iommu_get_bdf(sdev);
 
@@ -828,7 +827,8 @@ static void virtio_iommu_get_config(VirtIODevice *vdev, uint8_t *config_data)
                                   config->input_range.start,
                                   config->input_range.end,
                                   config->domain_range.end,
-                                  config->probe_size);
+                                  config->probe_size,
+                                  config->bypass);
     memcpy(config_data, &dev->config, sizeof(struct virtio_iommu_config));
 }
 
@@ -836,13 +836,29 @@ static void virtio_iommu_set_config(VirtIODevice *vdev,
                                       const uint8_t *config_data)
 {
     struct virtio_iommu_config config;
+    VirtIOIOMMU *dev = VIRTIO_IOMMU(vdev);
 
     memcpy(&config, config_data, sizeof(struct virtio_iommu_config));
+
+    if (config.bypass != dev->config.bypass) {
+        if (!virtio_vdev_has_feature(vdev, VIRTIO_IOMMU_F_BYPASS_CONFIG)) {
+            virtio_error(vdev, "cannot set config.bypass");
+            return;
+        }
+        if (config.bypass != 0 && config.bypass != 1) {
+            warn_report("invalid config.bypass value '%d'", config.bypass);
+            dev->config.bypass = 0;
+            return;
+        }
+        dev->config.bypass = config.bypass;
+    }
+
     trace_virtio_iommu_set_config(config.page_size_mask,
                                   config.input_range.start,
                                   config.input_range.end,
                                   config.domain_range.end,
-                                  config.probe_size);
+                                  config.probe_size,
+                                  config.bypass);
 }
 
 static uint64_t virtio_iommu_get_features(VirtIODevice *vdev, uint64_t f,
@@ -986,6 +1002,7 @@ static void virtio_iommu_device_realize(DeviceState *dev, Error **errp)
     s->config.input_range.end = -1UL;
     s->config.domain_range.end = 32;
     s->config.probe_size = VIOMMU_PROBE_SIZE;
+    s->config.bypass = s->boot_bypass;
 
     virtio_add_feature(&s->features, VIRTIO_RING_F_EVENT_IDX);
     virtio_add_feature(&s->features, VIRTIO_RING_F_INDIRECT_DESC);
@@ -993,9 +1010,9 @@ static void virtio_iommu_device_realize(DeviceState *dev, Error **errp)
     virtio_add_feature(&s->features, VIRTIO_IOMMU_F_INPUT_RANGE);
     virtio_add_feature(&s->features, VIRTIO_IOMMU_F_DOMAIN_RANGE);
     virtio_add_feature(&s->features, VIRTIO_IOMMU_F_MAP_UNMAP);
-    virtio_add_feature(&s->features, VIRTIO_IOMMU_F_BYPASS);
     virtio_add_feature(&s->features, VIRTIO_IOMMU_F_MMIO);
     virtio_add_feature(&s->features, VIRTIO_IOMMU_F_PROBE);
+    virtio_add_feature(&s->features, VIRTIO_IOMMU_F_BYPASS_CONFIG);
 
     qemu_mutex_init(&s->mutex);
 
@@ -1169,6 +1186,7 @@ static const VMStateDescription vmstate_virtio_iommu = {
 
 static Property virtio_iommu_properties[] = {
     DEFINE_PROP_LINK("primary-bus", VirtIOIOMMU, primary_bus, "PCI", PCIBus *),
+    DEFINE_PROP_BOOL("boot-bypass", VirtIOIOMMU, boot_bypass, true),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
index 8ed19e9d0c..6bc3821ba3 100644
--- a/hw/virtio/trace-events
+++ b/hw/virtio/trace-events
@@ -90,8 +90,8 @@ virtio_mmio_setting_irq(int level) "virtio_mmio setting IRQ %d"
 virtio_iommu_device_reset(void) "reset!"
 virtio_iommu_get_features(uint64_t features) "device supports features=0x%"PRIx64
 virtio_iommu_device_status(uint8_t status) "driver status = %d"
-virtio_iommu_get_config(uint64_t page_size_mask, uint64_t start, uint64_t end, uint32_t domain_range, uint32_t probe_size) "page_size_mask=0x%"PRIx64" start=0x%"PRIx64" end=0x%"PRIx64" domain_range=%d probe_size=0x%x"
-virtio_iommu_set_config(uint64_t page_size_mask, uint64_t start, uint64_t end, uint32_t domain_range, uint32_t probe_size) "page_size_mask=0x%"PRIx64" start=0x%"PRIx64" end=0x%"PRIx64" domain_bits=%d probe_size=0x%x"
+virtio_iommu_get_config(uint64_t page_size_mask, uint64_t start, uint64_t end, uint32_t domain_range, uint32_t probe_size, uint8_t bypass) "page_size_mask=0x%"PRIx64" start=0x%"PRIx64" end=0x%"PRIx64" domain_range=%d probe_size=0x%x bypass=0x%x"
+virtio_iommu_set_config(uint64_t page_size_mask, uint64_t start, uint64_t end, uint32_t domain_range, uint32_t probe_size, uint8_t bypass) "page_size_mask=0x%"PRIx64" start=0x%"PRIx64" end=0x%"PRIx64" domain_bits=%d probe_size=0x%x bypass=0x%x"
 virtio_iommu_attach(uint32_t domain_id, uint32_t ep_id) "domain=%d endpoint=%d"
 virtio_iommu_detach(uint32_t domain_id, uint32_t ep_id) "domain=%d endpoint=%d"
 virtio_iommu_map(uint32_t domain_id, uint64_t virt_start, uint64_t virt_end, uint64_t phys_start, uint32_t flags) "domain=%d virt_start=0x%"PRIx64" virt_end=0x%"PRIx64 " phys_start=0x%"PRIx64" flags=%d"
-- 
2.33.0

[PATCH 3/3] virtio-iommu: Support bypass domain

[Jean-Philippe Brucker]

The driver can create a bypass domain by passing the
VIRTIO_IOMMU_ATTACH_F_BYPASS flag on the ATTACH request. Bypass domains
perform slightly better than domains with identity mappings since they
skip translation.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 hw/virtio/virtio-iommu.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
index 82edeaa101..4f0207a3eb 100644
--- a/hw/virtio/virtio-iommu.c
+++ b/hw/virtio/virtio-iommu.c
@@ -42,6 +42,7 @@
 
 typedef struct VirtIOIOMMUDomain {
     uint32_t id;
+    bool bypass;
     GTree *mappings;
     QLIST_HEAD(, VirtIOIOMMUEndpoint) endpoint_list;
 } VirtIOIOMMUDomain;
@@ -257,12 +258,16 @@ static void virtio_iommu_put_endpoint(gpointer data)
 }
 
 static VirtIOIOMMUDomain *virtio_iommu_get_domain(VirtIOIOMMU *s,
-                                                  uint32_t domain_id)
+                                                  uint32_t domain_id,
+                                                  bool bypass)
 {
     VirtIOIOMMUDomain *domain;
 
     domain = g_tree_lookup(s->domains, GUINT_TO_POINTER(domain_id));
     if (domain) {
+        if (domain->bypass != bypass) {
+            return NULL;
+        }
         return domain;
     }
     domain = g_malloc0(sizeof(*domain));
@@ -270,6 +275,7 @@ static VirtIOIOMMUDomain *virtio_iommu_get_domain(VirtIOIOMMU *s,
     domain->mappings = g_tree_new_full((GCompareDataFunc)interval_cmp,
                                    NULL, (GDestroyNotify)g_free,
                                    (GDestroyNotify)g_free);
+    domain->bypass = bypass;
     g_tree_insert(s->domains, GUINT_TO_POINTER(domain_id), domain);
     QLIST_INIT(&domain->endpoint_list);
     trace_virtio_iommu_get_domain(domain_id);
@@ -333,11 +339,16 @@ static int virtio_iommu_attach(VirtIOIOMMU *s,
 {
     uint32_t domain_id = le32_to_cpu(req->domain);
     uint32_t ep_id = le32_to_cpu(req->endpoint);
+    uint32_t flags = le32_to_cpu(req->flags);
     VirtIOIOMMUDomain *domain;
     VirtIOIOMMUEndpoint *ep;
 
     trace_virtio_iommu_attach(domain_id, ep_id);
 
+    if (flags & ~VIRTIO_IOMMU_ATTACH_F_BYPASS) {
+        return VIRTIO_IOMMU_S_INVAL;
+    }
+
     ep = virtio_iommu_get_endpoint(s, ep_id);
     if (!ep) {
         return VIRTIO_IOMMU_S_NOENT;
@@ -355,7 +366,12 @@ static int virtio_iommu_attach(VirtIOIOMMU *s,
         }
     }
 
-    domain = virtio_iommu_get_domain(s, domain_id);
+    domain = virtio_iommu_get_domain(s, domain_id,
+                                     flags & VIRTIO_IOMMU_ATTACH_F_BYPASS);
+    if (!domain) {
+        /* Incompatible flags */
+        return VIRTIO_IOMMU_S_INVAL;
+    }
     QLIST_INSERT_HEAD(&domain->endpoint_list, ep, next);
 
     ep->domain = domain;
@@ -418,6 +434,10 @@ static int virtio_iommu_map(VirtIOIOMMU *s,
         return VIRTIO_IOMMU_S_NOENT;
     }
 
+    if (domain->bypass) {
+        return VIRTIO_IOMMU_S_INVAL;
+    }
+
     interval = g_malloc0(sizeof(*interval));
 
     interval->low = virt_start;
@@ -463,6 +483,11 @@ static int virtio_iommu_unmap(VirtIOIOMMU *s,
     if (!domain) {
         return VIRTIO_IOMMU_S_NOENT;
     }
+
+    if (domain->bypass) {
+        return VIRTIO_IOMMU_S_INVAL;
+    }
+
     interval.low = virt_start;
     interval.high = virt_end;
 
@@ -779,6 +804,9 @@ static IOMMUTLBEntry virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
             entry.perm = flag;
         }
         goto unlock;
+    } else if (ep->domain->bypass) {
+        entry.perm = flag;
+        goto unlock;
     }
 
     found = g_tree_lookup_extended(ep->domain->mappings, (gpointer)(&interval),
-- 
2.33.0

Re: [PATCH 2/3] virtio-iommu: Default to bypass during boot

[Eric Auger]

Hi jean,

On 9/30/21 8:50 PM, Jean-Philippe Brucker wrote:
> Currently the virtio-iommu device must be programmed before it allows
> DMA from any PCI device. This can make the VM entirely unusable when a
> virtio-iommu driver isn't present, for example in a bootloader that
> loads the OS from storage.
>
> Similarly to the other vIOMMU implementations, default to DMA bypassing
> the IOMMU during boot. Add a "boot-bypass" option that lets users change
> this behavior.
s/option/property
set to true by default.

Also mention this deprecates the legacy VIRTIO_IOMMU_F_BYPASS feature
>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> ---
>  include/hw/virtio/virtio-iommu.h |  1 +
>  hw/virtio/virtio-iommu.c         | 28 +++++++++++++++++++++++-----
>  hw/virtio/trace-events           |  4 ++--
>  3 files changed, 26 insertions(+), 7 deletions(-)
>
> diff --git a/include/hw/virtio/virtio-iommu.h b/include/hw/virtio/virtio-iommu.h
> index 273e35c04b..4c66989ca4 100644
> --- a/include/hw/virtio/virtio-iommu.h
> +++ b/include/hw/virtio/virtio-iommu.h
> @@ -58,6 +58,7 @@ struct VirtIOIOMMU {
>      GTree *domains;
>      QemuMutex mutex;
>      GTree *endpoints;
> +    bool boot_bypass;
>  };
>  
>  #endif
> diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
> index 1b23e8e18c..82edeaa101 100644
> --- a/hw/virtio/virtio-iommu.c
> +++ b/hw/virtio/virtio-iommu.c
> @@ -728,8 +728,7 @@ static IOMMUTLBEntry virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
>          .perm = IOMMU_NONE,
>      };
>  
> -    bypass_allowed = virtio_vdev_has_feature(&s->parent_obj,
> -                                             VIRTIO_IOMMU_F_BYPASS);
> +    bypass_allowed = s->config.bypass;
>  
>      sid = virtio_iommu_get_bdf(sdev);
>  
> @@ -828,7 +827,8 @@ static void virtio_iommu_get_config(VirtIODevice *vdev, uint8_t *config_data)
>                                    config->input_range.start,
>                                    config->input_range.end,
>                                    config->domain_range.end,
> -                                  config->probe_size);
> +                                  config->probe_size,
> +                                  config->bypass);
>      memcpy(config_data, &dev->config, sizeof(struct virtio_iommu_config));
>  }
>  
> @@ -836,13 +836,29 @@ static void virtio_iommu_set_config(VirtIODevice *vdev,
>                                        const uint8_t *config_data)
>  {
>      struct virtio_iommu_config config;
> +    VirtIOIOMMU *dev = VIRTIO_IOMMU(vdev);
>  
>      memcpy(&config, config_data, sizeof(struct virtio_iommu_config));
> +
> +    if (config.bypass != dev->config.bypass) {
> +        if (!virtio_vdev_has_feature(vdev, VIRTIO_IOMMU_F_BYPASS_CONFIG)) {
> +            virtio_error(vdev, "cannot set config.bypass");
> +            return;
> +        }
> +        if (config.bypass != 0 && config.bypass != 1) {
> +            warn_report("invalid config.bypass value '%d'", config.bypass);
> +            dev->config.bypass = 0;
Shouldn't we leave the old value instead. The spec proposal says it
takes 0 though.
> +            return;
> +        }
> +        dev->config.bypass = config.bypass;
> +    }
> +
>      trace_virtio_iommu_set_config(config.page_size_mask,
>                                    config.input_range.start,
>                                    config.input_range.end,
>                                    config.domain_range.end,
> -                                  config.probe_size);
> +                                  config.probe_size,
> +                                  config.bypass);
>  }
>  
>  static uint64_t virtio_iommu_get_features(VirtIODevice *vdev, uint64_t f,
> @@ -986,6 +1002,7 @@ static void virtio_iommu_device_realize(DeviceState *dev, Error **errp)
>      s->config.input_range.end = -1UL;
>      s->config.domain_range.end = 32;
>      s->config.probe_size = VIOMMU_PROBE_SIZE;
> +    s->config.bypass = s->boot_bypass;
>  
>      virtio_add_feature(&s->features, VIRTIO_RING_F_EVENT_IDX);
>      virtio_add_feature(&s->features, VIRTIO_RING_F_INDIRECT_DESC);
> @@ -993,9 +1010,9 @@ static void virtio_iommu_device_realize(DeviceState *dev, Error **errp)
>      virtio_add_feature(&s->features, VIRTIO_IOMMU_F_INPUT_RANGE);
>      virtio_add_feature(&s->features, VIRTIO_IOMMU_F_DOMAIN_RANGE);
>      virtio_add_feature(&s->features, VIRTIO_IOMMU_F_MAP_UNMAP);
> -    virtio_add_feature(&s->features, VIRTIO_IOMMU_F_BYPASS);
>      virtio_add_feature(&s->features, VIRTIO_IOMMU_F_MMIO);
>      virtio_add_feature(&s->features, VIRTIO_IOMMU_F_PROBE);
> +    virtio_add_feature(&s->features, VIRTIO_IOMMU_F_BYPASS_CONFIG);
>  
>      qemu_mutex_init(&s->mutex);
>  
> @@ -1169,6 +1186,7 @@ static const VMStateDescription vmstate_virtio_iommu = {
>  
>  static Property virtio_iommu_properties[] = {
>      DEFINE_PROP_LINK("primary-bus", VirtIOIOMMU, primary_bus, "PCI", PCIBus *),
> +    DEFINE_PROP_BOOL("boot-bypass", VirtIOIOMMU, boot_bypass, true),
>      DEFINE_PROP_END_OF_LIST(),
>  };
>  
> diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
> index 8ed19e9d0c..6bc3821ba3 100644
> --- a/hw/virtio/trace-events
> +++ b/hw/virtio/trace-events
> @@ -90,8 +90,8 @@ virtio_mmio_setting_irq(int level) "virtio_mmio setting IRQ %d"
>  virtio_iommu_device_reset(void) "reset!"
>  virtio_iommu_get_features(uint64_t features) "device supports features=0x%"PRIx64
>  virtio_iommu_device_status(uint8_t status) "driver status = %d"
> -virtio_iommu_get_config(uint64_t page_size_mask, uint64_t start, uint64_t end, uint32_t domain_range, uint32_t probe_size) "page_size_mask=0x%"PRIx64" start=0x%"PRIx64" end=0x%"PRIx64" domain_range=%d probe_size=0x%x"
> -virtio_iommu_set_config(uint64_t page_size_mask, uint64_t start, uint64_t end, uint32_t domain_range, uint32_t probe_size) "page_size_mask=0x%"PRIx64" start=0x%"PRIx64" end=0x%"PRIx64" domain_bits=%d probe_size=0x%x"
> +virtio_iommu_get_config(uint64_t page_size_mask, uint64_t start, uint64_t end, uint32_t domain_range, uint32_t probe_size, uint8_t bypass) "page_size_mask=0x%"PRIx64" start=0x%"PRIx64" end=0x%"PRIx64" domain_range=%d probe_size=0x%x bypass=0x%x"
> +virtio_iommu_set_config(uint64_t page_size_mask, uint64_t start, uint64_t end, uint32_t domain_range, uint32_t probe_size, uint8_t bypass) "page_size_mask=0x%"PRIx64" start=0x%"PRIx64" end=0x%"PRIx64" domain_bits=%d probe_size=0x%x bypass=0x%x"
>  virtio_iommu_attach(uint32_t domain_id, uint32_t ep_id) "domain=%d endpoint=%d"
>  virtio_iommu_detach(uint32_t domain_id, uint32_t ep_id) "domain=%d endpoint=%d"
>  virtio_iommu_map(uint32_t domain_id, uint64_t virt_start, uint64_t virt_end, uint64_t phys_start, uint32_t flags) "domain=%d virt_start=0x%"PRIx64" virt_end=0x%"PRIx64 " phys_start=0x%"PRIx64" flags=%d"
Thanks

Eric

Re: [PATCH 3/3] virtio-iommu: Support bypass domain

[Eric Auger]

Hi jean,

On 9/30/21 8:50 PM, Jean-Philippe Brucker wrote:
> The driver can create a bypass domain by passing the
> VIRTIO_IOMMU_ATTACH_F_BYPASS flag on the ATTACH request. Bypass domains
> perform slightly better than domains with identity mappings since they
> skip translation.
>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> ---
>  hw/virtio/virtio-iommu.c | 32 ++++++++++++++++++++++++++++++--
>  1 file changed, 30 insertions(+), 2 deletions(-)
>
> diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
> index 82edeaa101..4f0207a3eb 100644
> --- a/hw/virtio/virtio-iommu.c
> +++ b/hw/virtio/virtio-iommu.c
> @@ -42,6 +42,7 @@
>  
>  typedef struct VirtIOIOMMUDomain {
>      uint32_t id;
> +    bool bypass;
>      GTree *mappings;
>      QLIST_HEAD(, VirtIOIOMMUEndpoint) endpoint_list;
>  } VirtIOIOMMUDomain;
> @@ -257,12 +258,16 @@ static void virtio_iommu_put_endpoint(gpointer data)
>  }
>  
>  static VirtIOIOMMUDomain *virtio_iommu_get_domain(VirtIOIOMMU *s,
> -                                                  uint32_t domain_id)
> +                                                  uint32_t domain_id,
> +                                                  bool bypass)
>  {
>      VirtIOIOMMUDomain *domain;
>  
>      domain = g_tree_lookup(s->domains, GUINT_TO_POINTER(domain_id));
>      if (domain) {
> +        if (domain->bypass != bypass) {
> +            return NULL;
> +        }
>          return domain;
>      }
>      domain = g_malloc0(sizeof(*domain));
> @@ -270,6 +275,7 @@ static VirtIOIOMMUDomain *virtio_iommu_get_domain(VirtIOIOMMU *s,
>      domain->mappings = g_tree_new_full((GCompareDataFunc)interval_cmp,
>                                     NULL, (GDestroyNotify)g_free,
>                                     (GDestroyNotify)g_free);
> +    domain->bypass = bypass;
>      g_tree_insert(s->domains, GUINT_TO_POINTER(domain_id), domain);
>      QLIST_INIT(&domain->endpoint_list);
>      trace_virtio_iommu_get_domain(domain_id);
> @@ -333,11 +339,16 @@ static int virtio_iommu_attach(VirtIOIOMMU *s,
>  {
>      uint32_t domain_id = le32_to_cpu(req->domain);
>      uint32_t ep_id = le32_to_cpu(req->endpoint);
> +    uint32_t flags = le32_to_cpu(req->flags);
>      VirtIOIOMMUDomain *domain;
>      VirtIOIOMMUEndpoint *ep;
>  
>      trace_virtio_iommu_attach(domain_id, ep_id);
>  
> +    if (flags & ~VIRTIO_IOMMU_ATTACH_F_BYPASS) {
> +        return VIRTIO_IOMMU_S_INVAL;
> +    }
> +
>      ep = virtio_iommu_get_endpoint(s, ep_id);
>      if (!ep) {
>          return VIRTIO_IOMMU_S_NOENT;
> @@ -355,7 +366,12 @@ static int virtio_iommu_attach(VirtIOIOMMU *s,
>          }
>      }
>  
> -    domain = virtio_iommu_get_domain(s, domain_id);
> +    domain = virtio_iommu_get_domain(s, domain_id,
> +                                     flags & VIRTIO_IOMMU_ATTACH_F_BYPASS);
> +    if (!domain) {
> +        /* Incompatible flags */
Incompatible bypass flag
> +        return VIRTIO_IOMMU_S_INVAL;
> +    }
>      QLIST_INSERT_HEAD(&domain->endpoint_list, ep, next);
>  
>      ep->domain = domain;
> @@ -418,6 +434,10 @@ static int virtio_iommu_map(VirtIOIOMMU *s,
>          return VIRTIO_IOMMU_S_NOENT;
>      }
>  
> +    if (domain->bypass) {
> +        return VIRTIO_IOMMU_S_INVAL;
> +    }
> +
>      interval = g_malloc0(sizeof(*interval));
>  
>      interval->low = virt_start;
> @@ -463,6 +483,11 @@ static int virtio_iommu_unmap(VirtIOIOMMU *s,
>      if (!domain) {
>          return VIRTIO_IOMMU_S_NOENT;
>      }
> +
> +    if (domain->bypass) {
> +        return VIRTIO_IOMMU_S_INVAL;
> +    }
> +
>      interval.low = virt_start;
>      interval.high = virt_end;
>  
> @@ -779,6 +804,9 @@ static IOMMUTLBEntry virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
>              entry.perm = flag;
>          }
>          goto unlock;
> +    } else if (ep->domain->bypass) {
> +        entry.perm = flag;
> +        goto unlock;
>      }
>  
>      found = g_tree_lookup_extended(ep->domain->mappings, (gpointer)(&interval),
Otherwise looks good to me.

Eric

Re: [PATCH 2/3] virtio-iommu: Default to bypass during boot

[Jean-Philippe Brucker]

On Wed, Oct 06, 2021 at 03:04:15PM +0200, Eric Auger wrote:
> > +    if (config.bypass != dev->config.bypass) {
> > +        if (!virtio_vdev_has_feature(vdev, VIRTIO_IOMMU_F_BYPASS_CONFIG)) {
> > +            virtio_error(vdev, "cannot set config.bypass");
> > +            return;
> > +        }
> > +        if (config.bypass != 0 && config.bypass != 1) {
> > +            warn_report("invalid config.bypass value '%d'", config.bypass);
> > +            dev->config.bypass = 0;
> Shouldn't we leave the old value instead. The spec proposal says it
> takes 0 though.

Yes keeping the old value is better, I'll change the spec. Writing a
different value is a driver bug since new values for the bypass field will
be keyed off a new feature bit.

Thanks,
Jean

Re: [PATCH 0/3] virtio-iommu: Support VIRTIO_IOMMU_F_BYPASS_CONFIG

[Eric Auger]

Hi Jean, Michael,

On 9/30/21 8:50 PM, Jean-Philippe Brucker wrote:
> Replace the VIRTIO_IOMMU_F_BYPASS feature with
> VIRTIO_IOMMU_F_BYPASS_CONFIG, which enables a config space bit to switch
> global bypass on and off.
>
> Add a boot-bypass option, which defaults to 'on' to be in line with
> other vIOMMUs and to allow running firmware/bootloader that are unaware
> of the IOMMU.
>
> See the spec change for more rationale
> https://lists.oasis-open.org/archives/virtio-dev/202109/msg00137.html

I guess the kernel bits should be merged in 5.17?

Thanks

Eric
>
> Jean-Philippe Brucker (3):
>   NOMERGE: virtio-iommu: Add definitions for
>     VIRTIO_IOMMU_F_BYPASS_CONFIG
>   virtio-iommu: Default to bypass during boot
>   virtio-iommu: Support bypass domain
>
>  include/hw/virtio/virtio-iommu.h              |  1 +
>  include/standard-headers/linux/virtio_iommu.h | 10 +++-
>  hw/virtio/virtio-iommu.c                      | 60 ++++++++++++++++---
>  hw/virtio/trace-events                        |  4 +-
>  4 files changed, 64 insertions(+), 11 deletions(-)
>

Re: [PATCH 0/3] virtio-iommu: Support VIRTIO_IOMMU_F_BYPASS_CONFIG

[Jean-Philippe Brucker]

Hi Eric,

On Tue, Jan 11, 2022 at 10:02:12AM +0100, Eric Auger wrote:
> Hi Jean, Michael,
> 
> On 9/30/21 8:50 PM, Jean-Philippe Brucker wrote:
> > Replace the VIRTIO_IOMMU_F_BYPASS feature with
> > VIRTIO_IOMMU_F_BYPASS_CONFIG, which enables a config space bit to switch
> > global bypass on and off.
> >
> > Add a boot-bypass option, which defaults to 'on' to be in line with
> > other vIOMMUs and to allow running firmware/bootloader that are unaware
> > of the IOMMU.
> >
> > See the spec change for more rationale
> > https://lists.oasis-open.org/archives/virtio-dev/202109/msg00137.html
> 
> I guess the kernel bits should be merged in 5.17?

Yes, they should. I can resend at 5.17-rc1 along with a commit updating
the linux headers. Or is there a specific process for synchronizing the
headers?  Looking at git log it looks like scripts/update-linux-headers.sh
is run by whomever needs new UAPI features.

Thanks,
Jean

Re: [PATCH 0/3] virtio-iommu: Support VIRTIO_IOMMU_F_BYPASS_CONFIG

[Eric Auger]

Hi Jean,

On 1/11/22 11:13 AM, Jean-Philippe Brucker wrote:
> Hi Eric,
>
> On Tue, Jan 11, 2022 at 10:02:12AM +0100, Eric Auger wrote:
>> Hi Jean, Michael,
>>
>> On 9/30/21 8:50 PM, Jean-Philippe Brucker wrote:
>>> Replace the VIRTIO_IOMMU_F_BYPASS feature with
>>> VIRTIO_IOMMU_F_BYPASS_CONFIG, which enables a config space bit to switch
>>> global bypass on and off.
>>>
>>> Add a boot-bypass option, which defaults to 'on' to be in line with
>>> other vIOMMUs and to allow running firmware/bootloader that are unaware
>>> of the IOMMU.
>>>
>>> See the spec change for more rationale
>>> https://lists.oasis-open.org/archives/virtio-dev/202109/msg00137.html
>> I guess the kernel bits should be merged in 5.17?
> Yes, they should. I can resend at 5.17-rc1 along with a commit updating
> the linux headers. Or is there a specific process for synchronizing the
> headers?  Looking at git log it looks like scripts/update-linux-headers.sh
> is run by whomever needs new UAPI features.
yes you need to generate the header update patch using

scripts/update-linux-headers.sh once the kernel pieces have landed

Thanks

Eric

>
> Thanks,
> Jean
>

Re: [PATCH 0/3] virtio-iommu: Support VIRTIO_IOMMU_F_BYPASS_CONFIG

[Michael S. Tsirkin]

On Tue, Jan 11, 2022 at 10:02:12AM +0100, Eric Auger wrote:
> Hi Jean, Michael,
> 
> On 9/30/21 8:50 PM, Jean-Philippe Brucker wrote:
> > Replace the VIRTIO_IOMMU_F_BYPASS feature with
> > VIRTIO_IOMMU_F_BYPASS_CONFIG, which enables a config space bit to switch
> > global bypass on and off.
> >
> > Add a boot-bypass option, which defaults to 'on' to be in line with
> > other vIOMMUs and to allow running firmware/bootloader that are unaware
> > of the IOMMU.
> >
> > See the spec change for more rationale
> > https://lists.oasis-open.org/archives/virtio-dev/202109/msg00137.html
> 
> I guess the kernel bits should be merged in 5.17?
> 
> Thanks
> 
> Eric

They are in fact in my tree and set to go into 5.16.
They've been in linux-next for a whole cycle now.
But if you feel I'm rushing things, pls let me know.
Also, pls let me know whether my tree actually works well for you!

> >
> > Jean-Philippe Brucker (3):
> >   NOMERGE: virtio-iommu: Add definitions for
> >     VIRTIO_IOMMU_F_BYPASS_CONFIG
> >   virtio-iommu: Default to bypass during boot
> >   virtio-iommu: Support bypass domain
> >
> >  include/hw/virtio/virtio-iommu.h              |  1 +
> >  include/standard-headers/linux/virtio_iommu.h | 10 +++-
> >  hw/virtio/virtio-iommu.c                      | 60 ++++++++++++++++---
> >  hw/virtio/trace-events                        |  4 +-
> >  4 files changed, 64 insertions(+), 11 deletions(-)
> >

Re: [PATCH 0/3] virtio-iommu: Support VIRTIO_IOMMU_F_BYPASS_CONFIG

[Jean-Philippe Brucker]

Hi Michael,

On Tue, Jan 11, 2022 at 10:40:28AM -0500, Michael S. Tsirkin wrote:
> On Tue, Jan 11, 2022 at 10:02:12AM +0100, Eric Auger wrote:
> > Hi Jean, Michael,
> > 
> > On 9/30/21 8:50 PM, Jean-Philippe Brucker wrote:
> > > Replace the VIRTIO_IOMMU_F_BYPASS feature with
> > > VIRTIO_IOMMU_F_BYPASS_CONFIG, which enables a config space bit to switch
> > > global bypass on and off.
> > >
> > > Add a boot-bypass option, which defaults to 'on' to be in line with
> > > other vIOMMUs and to allow running firmware/bootloader that are unaware
> > > of the IOMMU.
> > >
> > > See the spec change for more rationale
> > > https://lists.oasis-open.org/archives/virtio-dev/202109/msg00137.html
> > 
> > I guess the kernel bits should be merged in 5.17?
> > 
> > Thanks
> > 
> > Eric
> 
> They are in fact in my tree and set to go into 5.16.
> They've been in linux-next for a whole cycle now.
> But if you feel I'm rushing things, pls let me know.
> Also, pls let me know whether my tree actually works well for you!

Thanks, unfortunately I just noticed that those patches are from an older
version of the series, the latest being v3
https://lore.kernel.org/linux-iommu/20211201173323.1045819-1-jean-philippe@linaro.org/

Since Joerg picked the latest one in his tree [1], I was wondering if you
could drop those patches?

51a4c54f35ae iommu/virtio: Support identity-mapped domains
523e55a406aa iommu/virtio: Pass end address to viommu_add_mapping()
97301219dfb2 iommu/virtio: Sort reserved regions
720552613526 iommu/virtio: Support bypass domains
01444b9c772f iommu/virtio: Add definitions for VIRTIO_IOMMU_F_BYPASS_CONFIG

Thanks,
Jean

[1] https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git/