[RFC 0/3] virtio-gpu: Shared memory capability

[RFC 0/3] virtio-gpu: Shared memory capability

[Antonio Caggiano]

Previously 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.

RFC as I believe it needs a proper review from both authors of first two
commits.

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

Antonio Caggiano (1):
  virtio: Fix shared memory capability

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(-)

-- 
2.30.2

[RFC 1/3] 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 182e0868b0..63eff0e697 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 24c6628944..835ebcb1a0 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;
-- 
2.30.2

[RFC 2/3] 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'.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
(cherry picked from commit a5d628a3a3c5e60b98b15ffff197c36a77056115)
---
 hw/virtio/virtio-pci.c                      | 19 +++++++++++++++++++
 hw/virtio/virtio-pci.h                      |  4 ++++
 include/standard-headers/linux/virtio_pci.h |  7 +++++++
 3 files changed, 30 insertions(+)

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 6e16e2705c..9c7b8942c8 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_shm_cap 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.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
diff --git a/include/standard-headers/linux/virtio_pci.h b/include/standard-headers/linux/virtio_pci.h
index db7a8e2fcb..85d1420d29 100644
--- a/include/standard-headers/linux/virtio_pci.h
+++ b/include/standard-headers/linux/virtio_pci.h
@@ -172,6 +172,13 @@ struct virtio_pci_cfg_cap {
 	uint8_t pci_cfg_data[4]; /* Data for BAR access. */
 };
 
+struct virtio_pci_shm_cap {
+	struct virtio_pci_cap cap;
+	uint32_t offset_hi;             /* Most sig 32 bits of offset */
+	uint32_t length_hi;             /* Most sig 32 bits of length */
+	uint8_t  id;                    /* To distinguish shm chunks */
+};
+
 /* Macro versions of offsets for the Old Timers! */
 #define VIRTIO_PCI_CAP_VNDR		0
 #define VIRTIO_PCI_CAP_NEXT		1
-- 
2.30.2

[RFC 3/3] virtio: Fix shared memory capability

[Antonio Caggiano]

Remove virtio_pci_shm_cap as virtio_pci_cap64 should be used instead.

Signed-off-by: Antonio Caggiano <antonio.caggiano@collabora.com>
---
 hw/virtio/virtio-pci.c                      | 4 ++--
 include/standard-headers/linux/virtio_pci.h | 7 -------
 2 files changed, 2 insertions(+), 9 deletions(-)

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 9c7b8942c8..200f1e38ef 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1166,7 +1166,7 @@ int virtio_pci_add_shm_cap(VirtIOPCIProxy *proxy,
                            uint8_t bar, uint64_t offset, uint64_t length,
                            uint8_t id)
 {
-    struct virtio_pci_shm_cap cap = {
+    struct virtio_pci_cap64 cap = {
         .cap.cap_len = sizeof cap,
         .cap.cfg_type = VIRTIO_PCI_CAP_SHARED_MEMORY_CFG,
     };
@@ -1177,7 +1177,7 @@ int virtio_pci_add_shm_cap(VirtIOPCIProxy *proxy,
     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.id = id;
+    cap.cap.id = id;
     return virtio_pci_add_mem_cap(proxy, &cap.cap);
 }
 
diff --git a/include/standard-headers/linux/virtio_pci.h b/include/standard-headers/linux/virtio_pci.h
index 85d1420d29..db7a8e2fcb 100644
--- a/include/standard-headers/linux/virtio_pci.h
+++ b/include/standard-headers/linux/virtio_pci.h
@@ -172,13 +172,6 @@ struct virtio_pci_cfg_cap {
 	uint8_t pci_cfg_data[4]; /* Data for BAR access. */
 };
 
-struct virtio_pci_shm_cap {
-	struct virtio_pci_cap cap;
-	uint32_t offset_hi;             /* Most sig 32 bits of offset */
-	uint32_t length_hi;             /* Most sig 32 bits of length */
-	uint8_t  id;                    /* To distinguish shm chunks */
-};
-
 /* Macro versions of offsets for the Old Timers! */
 #define VIRTIO_PCI_CAP_VNDR		0
 #define VIRTIO_PCI_CAP_NEXT		1
-- 
2.30.2

Re: [RFC 0/3] virtio-gpu: Shared memory capability

[Gerd Hoffmann]

On Tue, Sep 28, 2021 at 03:15:45PM +0200, Antonio Caggiano wrote:
> Previously 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.
> 
> RFC as I believe it needs a proper review from both authors of first two
> commits.

Looks sane on a quick glance.  I'd tend to squash patch #3 into patch #2.
Doesn't make much sense standalone though ...

take care,
  Gerd