[PATCH 0/2] virtio-gpu: Shared memory capability

[PATCH 0/2] virtio-gpu: Shared memory capability

[Antonio Caggiano]

Previously RFC [0] part of [0], now a patch series on its own.

This patch series cherry picks two commits from [1] and applies one fix
according to [2], which should answer Gerd's comment [3] on previous
patch.

[0] https://www.mail-archive.com/qemu-devel@nongnu.org/msg840405.html
[1] https://www.mail-archive.com/qemu-devel@nongnu.org/msg826897.html
[2] https://gitlab.freedesktop.org/virgl/qemu/-/commits/virtio-gpu-next/
[3] https://github.com/torvalds/linux/commit/0dd4ff93f4c8dba016ad79384007da4938cd54a1
[4] https://www.mail-archive.com/qemu-devel@nongnu.org/msg827306.html

Dr. David Alan Gilbert (1):
  virtio: Add shared memory capability

Gerd Hoffmann (1):
  virtio-gpu: hostmem

 hw/display/virtio-gpu-pci.c    | 14 ++++++++++++++
 hw/display/virtio-gpu.c        |  1 +
 hw/display/virtio-vga.c        | 32 +++++++++++++++++++++++---------
 hw/virtio/virtio-pci.c         | 19 +++++++++++++++++++
 hw/virtio/virtio-pci.h         |  4 ++++
 include/hw/virtio/virtio-gpu.h |  5 +++++
 6 files changed, 66 insertions(+), 9 deletions(-)

-- 
2.32.0

[PATCH 1/2] virtio-gpu: hostmem

[Antonio Caggiano]

From: Gerd Hoffmann <kraxel@redhat.com>

Use VIRTIO_GPU_SHM_ID_HOST_VISIBLE as id for virtio-gpu.

Signed-off-by: Antonio Caggiano <antonio.caggiano@collabora.com>
---
 hw/display/virtio-gpu-pci.c    | 14 ++++++++++++++
 hw/display/virtio-gpu.c        |  1 +
 hw/display/virtio-vga.c        | 32 +++++++++++++++++++++++---------
 include/hw/virtio/virtio-gpu.h |  5 +++++
 4 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/hw/display/virtio-gpu-pci.c b/hw/display/virtio-gpu-pci.c
index e36eee0c40..a79bd751b2 100644
--- a/hw/display/virtio-gpu-pci.c
+++ b/hw/display/virtio-gpu-pci.c
@@ -33,6 +33,20 @@ static void virtio_gpu_pci_base_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
     DeviceState *vdev = DEVICE(g);
     int i;
 
+    if (virtio_gpu_hostmem_enabled(g->conf)) {
+        vpci_dev->msix_bar_idx = 1;
+        vpci_dev->modern_mem_bar_idx = 2;
+        memory_region_init(&g->hostmem, OBJECT(g), "virtio-gpu-hostmem",
+                           g->conf.hostmem);
+        pci_register_bar(&vpci_dev->pci_dev, 4,
+                         PCI_BASE_ADDRESS_SPACE_MEMORY |
+                         PCI_BASE_ADDRESS_MEM_PREFETCH |
+                         PCI_BASE_ADDRESS_MEM_TYPE_64,
+                         &g->hostmem);
+        virtio_pci_add_shm_cap(vpci_dev, 4, 0, g->conf.hostmem, VIRTIO_GPU_SHM_ID_HOST_VISIBLE);
+    }
+
+    qdev_set_parent_bus(vdev, BUS(&vpci_dev->bus), errp);
     virtio_pci_force_virtio_1(vpci_dev);
     if (!qdev_realize(vdev, BUS(&vpci_dev->bus), errp)) {
         return;
diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
index d78b9700c7..1cfcb81c1b 100644
--- a/hw/display/virtio-gpu.c
+++ b/hw/display/virtio-gpu.c
@@ -1418,6 +1418,7 @@ static Property virtio_gpu_properties[] = {
                      256 * MiB),
     DEFINE_PROP_BIT("blob", VirtIOGPU, parent_obj.conf.flags,
                     VIRTIO_GPU_FLAG_BLOB_ENABLED, false),
+    DEFINE_PROP_SIZE("hostmem", VirtIOGPU, parent_obj.conf.hostmem, 0),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/hw/display/virtio-vga.c b/hw/display/virtio-vga.c
index 9e57f61e9e..ca841a0799 100644
--- a/hw/display/virtio-vga.c
+++ b/hw/display/virtio-vga.c
@@ -125,16 +125,30 @@ static void virtio_vga_base_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
     pci_register_bar(&vpci_dev->pci_dev, 0,
                      PCI_BASE_ADDRESS_MEM_PREFETCH, &vga->vram);
 
-    /*
-     * Configure virtio bar and regions
-     *
-     * We use bar #2 for the mmio regions, to be compatible with stdvga.
-     * virtio regions are moved to the end of bar #2, to make room for
-     * the stdvga mmio registers at the start of bar #2.
-     */
-    vpci_dev->modern_mem_bar_idx = 2;
-    vpci_dev->msix_bar_idx = 4;
     vpci_dev->modern_io_bar_idx = 5;
+  
+    if (!virtio_gpu_hostmem_enabled(g->conf)) {
+        /*
+        * Configure virtio bar and regions
+        *
+        * We use bar #2 for the mmio regions, to be compatible with stdvga.
+        * virtio regions are moved to the end of bar #2, to make room for
+        * the stdvga mmio registers at the start of bar #2.
+        */
+        vpci_dev->modern_mem_bar_idx = 2;
+        vpci_dev->msix_bar_idx = 4;
+    } else {
+        vpci_dev->msix_bar_idx = 1;
+        vpci_dev->modern_mem_bar_idx = 2;
+        memory_region_init(&g->hostmem, OBJECT(g), "virtio-gpu-hostmem",
+                           g->conf.hostmem);
+        pci_register_bar(&vpci_dev->pci_dev, 4,
+                         PCI_BASE_ADDRESS_SPACE_MEMORY |
+                         PCI_BASE_ADDRESS_MEM_PREFETCH |
+                         PCI_BASE_ADDRESS_MEM_TYPE_64,
+                         &g->hostmem);
+        virtio_pci_add_shm_cap(vpci_dev, 4, 0, g->conf.hostmem, VIRTIO_GPU_SHM_ID_HOST_VISIBLE);
+    }
 
     if (!(vpci_dev->flags & VIRTIO_PCI_FLAG_PAGE_PER_VQ)) {
         /*
diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
index acfba7c76c..3963cb4f86 100644
--- a/include/hw/virtio/virtio-gpu.h
+++ b/include/hw/virtio/virtio-gpu.h
@@ -102,12 +102,15 @@ enum virtio_gpu_base_conf_flags {
     (_cfg.flags & (1 << VIRTIO_GPU_FLAG_DMABUF_ENABLED))
 #define virtio_gpu_blob_enabled(_cfg) \
     (_cfg.flags & (1 << VIRTIO_GPU_FLAG_BLOB_ENABLED))
+#define virtio_gpu_hostmem_enabled(_cfg) \
+    (_cfg.hostmem > 0)
 
 struct virtio_gpu_base_conf {
     uint32_t max_outputs;
     uint32_t flags;
     uint32_t xres;
     uint32_t yres;
+    uint64_t hostmem;
 };
 
 struct virtio_gpu_ctrl_command {
@@ -131,6 +134,8 @@ struct VirtIOGPUBase {
     int renderer_blocked;
     int enable;
 
+    MemoryRegion hostmem;
+
     struct virtio_gpu_scanout scanout[VIRTIO_GPU_MAX_SCANOUTS];
 
     int enabled_output_bitmask;
-- 
2.32.0

[PATCH 2/2] virtio: Add shared memory capability

[Antonio Caggiano]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Define a new capability type 'VIRTIO_PCI_CAP_SHARED_MEMORY_CFG'
and the data structure 'virtio_pci_shm_cap' to go with it.
They allow defining shared memory regions with sizes and offsets
of 2^32 and more.
Multiple instances of the capability are allowed and distinguished
by a device-specific 'id'.

v2: Remove virtio_pci_shm_cap as virtio_pci_cap64 is used instead.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
(cherry picked from commit a5d628a3a3c5e60b98b15ffff197c36a77056115)
Signed-off-by: Antonio Caggiano <antonio.caggiano@collabora.com>
---
 hw/virtio/virtio-pci.c | 19 +++++++++++++++++++
 hw/virtio/virtio-pci.h |  4 ++++
 2 files changed, 23 insertions(+)

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 750aa47ec1..8152d3c1b3 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1162,6 +1162,25 @@ static int virtio_pci_add_mem_cap(VirtIOPCIProxy *proxy,
     return offset;
 }
 
+int virtio_pci_add_shm_cap(VirtIOPCIProxy *proxy,
+                           uint8_t bar, uint64_t offset, uint64_t length,
+                           uint8_t id)
+{
+    struct virtio_pci_cap64 cap = {
+        .cap.cap_len = sizeof cap,
+        .cap.cfg_type = VIRTIO_PCI_CAP_SHARED_MEMORY_CFG,
+    };
+    uint32_t mask32 = ~0;
+
+    cap.cap.bar = bar;
+    cap.cap.length = cpu_to_le32(length & mask32);
+    cap.length_hi = cpu_to_le32((length >> 32) & mask32);
+    cap.cap.offset = cpu_to_le32(offset & mask32);
+    cap.offset_hi = cpu_to_le32((offset >> 32) & mask32);
+    cap.cap.id = id;
+    return virtio_pci_add_mem_cap(proxy, &cap.cap);
+}
+
 static uint64_t virtio_pci_common_read(void *opaque, hwaddr addr,
                                        unsigned size)
 {
diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h
index 2446dcd9ae..5e5c4a4c6d 100644
--- a/hw/virtio/virtio-pci.h
+++ b/hw/virtio/virtio-pci.h
@@ -252,4 +252,8 @@ void virtio_pci_types_register(const VirtioPCIDeviceTypeInfo *t);
  */
 unsigned virtio_pci_optimal_num_queues(unsigned fixed_queues);
 
+int virtio_pci_add_shm_cap(VirtIOPCIProxy *proxy,
+                           uint8_t bar, uint64_t offset, uint64_t length,
+                           uint8_t id);
+
 #endif
-- 
2.32.0

Re: [PATCH 1/2] virtio-gpu: hostmem

[Michael S. Tsirkin]

On Wed, Nov 10, 2021 at 05:42:19PM +0100, Antonio Caggiano wrote:
> From: Gerd Hoffmann <kraxel@redhat.com>
> 
> Use VIRTIO_GPU_SHM_ID_HOST_VISIBLE as id for virtio-gpu.
> 
> Signed-off-by: Antonio Caggiano <antonio.caggiano@collabora.com>

I guess Gerd can apply this as appropriate.

Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>  hw/display/virtio-gpu-pci.c    | 14 ++++++++++++++
>  hw/display/virtio-gpu.c        |  1 +
>  hw/display/virtio-vga.c        | 32 +++++++++++++++++++++++---------
>  include/hw/virtio/virtio-gpu.h |  5 +++++
>  4 files changed, 43 insertions(+), 9 deletions(-)
> 
> diff --git a/hw/display/virtio-gpu-pci.c b/hw/display/virtio-gpu-pci.c
> index e36eee0c40..a79bd751b2 100644
> --- a/hw/display/virtio-gpu-pci.c
> +++ b/hw/display/virtio-gpu-pci.c
> @@ -33,6 +33,20 @@ static void virtio_gpu_pci_base_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
>      DeviceState *vdev = DEVICE(g);
>      int i;
>  
> +    if (virtio_gpu_hostmem_enabled(g->conf)) {
> +        vpci_dev->msix_bar_idx = 1;
> +        vpci_dev->modern_mem_bar_idx = 2;
> +        memory_region_init(&g->hostmem, OBJECT(g), "virtio-gpu-hostmem",
> +                           g->conf.hostmem);
> +        pci_register_bar(&vpci_dev->pci_dev, 4,
> +                         PCI_BASE_ADDRESS_SPACE_MEMORY |
> +                         PCI_BASE_ADDRESS_MEM_PREFETCH |
> +                         PCI_BASE_ADDRESS_MEM_TYPE_64,
> +                         &g->hostmem);
> +        virtio_pci_add_shm_cap(vpci_dev, 4, 0, g->conf.hostmem, VIRTIO_GPU_SHM_ID_HOST_VISIBLE);
> +    }
> +
> +    qdev_set_parent_bus(vdev, BUS(&vpci_dev->bus), errp);
>      virtio_pci_force_virtio_1(vpci_dev);
>      if (!qdev_realize(vdev, BUS(&vpci_dev->bus), errp)) {
>          return;
> diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
> index d78b9700c7..1cfcb81c1b 100644
> --- a/hw/display/virtio-gpu.c
> +++ b/hw/display/virtio-gpu.c
> @@ -1418,6 +1418,7 @@ static Property virtio_gpu_properties[] = {
>                       256 * MiB),
>      DEFINE_PROP_BIT("blob", VirtIOGPU, parent_obj.conf.flags,
>                      VIRTIO_GPU_FLAG_BLOB_ENABLED, false),
> +    DEFINE_PROP_SIZE("hostmem", VirtIOGPU, parent_obj.conf.hostmem, 0),
>      DEFINE_PROP_END_OF_LIST(),
>  };
>  
> diff --git a/hw/display/virtio-vga.c b/hw/display/virtio-vga.c
> index 9e57f61e9e..ca841a0799 100644
> --- a/hw/display/virtio-vga.c
> +++ b/hw/display/virtio-vga.c
> @@ -125,16 +125,30 @@ static void virtio_vga_base_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
>      pci_register_bar(&vpci_dev->pci_dev, 0,
>                       PCI_BASE_ADDRESS_MEM_PREFETCH, &vga->vram);
>  
> -    /*
> -     * Configure virtio bar and regions
> -     *
> -     * We use bar #2 for the mmio regions, to be compatible with stdvga.
> -     * virtio regions are moved to the end of bar #2, to make room for
> -     * the stdvga mmio registers at the start of bar #2.
> -     */
> -    vpci_dev->modern_mem_bar_idx = 2;
> -    vpci_dev->msix_bar_idx = 4;
>      vpci_dev->modern_io_bar_idx = 5;
> +  
> +    if (!virtio_gpu_hostmem_enabled(g->conf)) {
> +        /*
> +        * Configure virtio bar and regions
> +        *
> +        * We use bar #2 for the mmio regions, to be compatible with stdvga.
> +        * virtio regions are moved to the end of bar #2, to make room for
> +        * the stdvga mmio registers at the start of bar #2.
> +        */
> +        vpci_dev->modern_mem_bar_idx = 2;
> +        vpci_dev->msix_bar_idx = 4;
> +    } else {
> +        vpci_dev->msix_bar_idx = 1;
> +        vpci_dev->modern_mem_bar_idx = 2;
> +        memory_region_init(&g->hostmem, OBJECT(g), "virtio-gpu-hostmem",
> +                           g->conf.hostmem);
> +        pci_register_bar(&vpci_dev->pci_dev, 4,
> +                         PCI_BASE_ADDRESS_SPACE_MEMORY |
> +                         PCI_BASE_ADDRESS_MEM_PREFETCH |
> +                         PCI_BASE_ADDRESS_MEM_TYPE_64,
> +                         &g->hostmem);
> +        virtio_pci_add_shm_cap(vpci_dev, 4, 0, g->conf.hostmem, VIRTIO_GPU_SHM_ID_HOST_VISIBLE);
> +    }
>  
>      if (!(vpci_dev->flags & VIRTIO_PCI_FLAG_PAGE_PER_VQ)) {
>          /*
> diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
> index acfba7c76c..3963cb4f86 100644
> --- a/include/hw/virtio/virtio-gpu.h
> +++ b/include/hw/virtio/virtio-gpu.h
> @@ -102,12 +102,15 @@ enum virtio_gpu_base_conf_flags {
>      (_cfg.flags & (1 << VIRTIO_GPU_FLAG_DMABUF_ENABLED))
>  #define virtio_gpu_blob_enabled(_cfg) \
>      (_cfg.flags & (1 << VIRTIO_GPU_FLAG_BLOB_ENABLED))
> +#define virtio_gpu_hostmem_enabled(_cfg) \
> +    (_cfg.hostmem > 0)
>  

Don't much like the lower-case macro here, but I guess it's
consistent with rest of the code.

>  struct virtio_gpu_base_conf {
>      uint32_t max_outputs;
>      uint32_t flags;
>      uint32_t xres;
>      uint32_t yres;
> +    uint64_t hostmem;
>  };
>  
>  struct virtio_gpu_ctrl_command {
> @@ -131,6 +134,8 @@ struct VirtIOGPUBase {
>      int renderer_blocked;
>      int enable;
>  
> +    MemoryRegion hostmem;
> +
>      struct virtio_gpu_scanout scanout[VIRTIO_GPU_MAX_SCANOUTS];
>  
>      int enabled_output_bitmask;
> -- 
> 2.32.0

Re: [PATCH 2/2] virtio: Add shared memory capability

[Michael S. Tsirkin]

On Wed, Nov 10, 2021 at 05:42:20PM +0100, Antonio Caggiano wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> Define a new capability type 'VIRTIO_PCI_CAP_SHARED_MEMORY_CFG'
> and the data structure 'virtio_pci_shm_cap' to go with it.
> They allow defining shared memory regions with sizes and offsets
> of 2^32 and more.
> Multiple instances of the capability are allowed and distinguished
> by a device-specific 'id'.
> 
> v2: Remove virtio_pci_shm_cap as virtio_pci_cap64 is used instead.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> (cherry picked from commit a5d628a3a3c5e60b98b15ffff197c36a77056115)

Where's that commit? I think we should drop this, right?

> Signed-off-by: Antonio Caggiano <antonio.caggiano@collabora.com>
> ---
>  hw/virtio/virtio-pci.c | 19 +++++++++++++++++++
>  hw/virtio/virtio-pci.h |  4 ++++
>  2 files changed, 23 insertions(+)
> 
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 750aa47ec1..8152d3c1b3 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1162,6 +1162,25 @@ static int virtio_pci_add_mem_cap(VirtIOPCIProxy *proxy,
>      return offset;
>  }
>  
> +int virtio_pci_add_shm_cap(VirtIOPCIProxy *proxy,
> +                           uint8_t bar, uint64_t offset, uint64_t length,
> +                           uint8_t id)
> +{
> +    struct virtio_pci_cap64 cap = {
> +        .cap.cap_len = sizeof cap,
> +        .cap.cfg_type = VIRTIO_PCI_CAP_SHARED_MEMORY_CFG,
> +    };
> +    uint32_t mask32 = ~0;
> +
> +    cap.cap.bar = bar;
> +    cap.cap.length = cpu_to_le32(length & mask32);
> +    cap.length_hi = cpu_to_le32((length >> 32) & mask32);
> +    cap.cap.offset = cpu_to_le32(offset & mask32);
> +    cap.offset_hi = cpu_to_le32((offset >> 32) & mask32);
> +    cap.cap.id = id;
> +    return virtio_pci_add_mem_cap(proxy, &cap.cap);


You don't need & mask32 I think. cpu_to_le32 will truncate
the value.


> +}
> +
>  static uint64_t virtio_pci_common_read(void *opaque, hwaddr addr,
>                                         unsigned size)
>  {
> diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h
> index 2446dcd9ae..5e5c4a4c6d 100644
> --- a/hw/virtio/virtio-pci.h
> +++ b/hw/virtio/virtio-pci.h
> @@ -252,4 +252,8 @@ void virtio_pci_types_register(const VirtioPCIDeviceTypeInfo *t);
>   */
>  unsigned virtio_pci_optimal_num_queues(unsigned fixed_queues);
>  
> +int virtio_pci_add_shm_cap(VirtIOPCIProxy *proxy,
> +                           uint8_t bar, uint64_t offset, uint64_t length,
> +                           uint8_t id);
> +
>  #endif

So it's a new API, but where's the user?
I guess just include this patch with where-ever it's actually used.

> -- 
> 2.32.0

Re: [PATCH 2/2] virtio: Add shared memory capability

[Antonio Caggiano]

> Where's that commit? I think we should drop this, right? 

Yes, I will submit another version without that line.

> You don't need & mask32 I think. cpu_to_le32 will truncate
> the value.

Makes sense, will be fixed in next version.

> So it's a new API, but where's the user?
> I guess just include this patch with where-ever it's actually used.

The user of virtio_pci_add_shm_cap is in the previous commits.



My original patch [0] was actually a squash of the current two commits, 
but Dr. David Alan Gilbert explicitly asked me [1] to split them in 
order to preserve his original virtio-pci patch [2]. I could squash 
these two commits together again, but we will be back to square one [1].



[0] https://www.mail-archive.com/qemu-devel@nongnu.org/msg826814.html

[1] https://www.mail-archive.com/qemu-devel@nongnu.org/msg826890.html

[2] 
https://gitlab.freedesktop.org/virgl/qemu/-/commit/7fa847fde7143ca2ef5b0a2a13c5f669d3beb195