From ff5e61b600d9a130faad32ceda3cd212dcb387d4 Mon Sep 17 00:00:00 2001

From: David Gibson <dgibson@redhat.com>

Date: Thu, 16 Nov 2017 03:07:11 +0100

Subject: [PATCH 07/30] virtio-pci: Replace modern_as with direct access to

 modern_bar

RH-Author: David Gibson <dgibson@redhat.com>

Message-id: <20171116030732.8560-2-dgibson@redhat.com>

Patchwork-id: 77689

O-Subject: [PATCH 01/22] virtio-pci: Replace modern_as with direct access to modern_bar

Bugzilla: 1481593

RH-Acked-by: Thomas Huth <thuth@redhat.com>

RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

RH-Acked-by: Eduardo Habkost <ehabkost@redhat.com>

RH-Acked-by: Laurent Vivier <lvivier@redhat.com>

From: Alexey Kardashevskiy <aik@ozlabs.ru>

The modern bar is accessed now via yet another address space created just

for that purpose and it does not really need FlatView and dispatch tree

as it has a single memory region so it is just a waste of memory. Things

get even worse when there are dozens or hundreds of virtio-pci devices -

since these address spaces are global, changing any of them triggers

rebuilding all address spaces.

This replaces indirect accesses to the modern BAR with a simple lookup

and direct calls to memory_region_dispatch_read/write.

This is expected to save lots of memory at boot time after applying:

[Qemu-devel] [PULL 00/32] Misc changes for 2017-09-22

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

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

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

(cherry picked from commit a93c8d828af186d9a6a1c915a1be8ba22fb89849)

Signed-off-by: David Gibson <dgibson@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 hw/virtio/virtio-pci.c | 75 +++++++++++++++++++++++++++++---------------------

 hw/virtio/virtio-pci.h | 17 +++++++-----

 2 files changed, 54 insertions(+), 38 deletions(-)

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c

index 6e497c8..4b041bb 100644

--- a/hw/virtio/virtio-pci.c

+++ b/hw/virtio/virtio-pci.c

@@ -545,6 +545,24 @@ static const MemoryRegionOps virtio_pci_config_ops = {

     .endianness = DEVICE_LITTLE_ENDIAN,

 };

+static MemoryRegion *virtio_address_space_lookup(VirtIOPCIProxy *proxy,

+                                                 hwaddr *off, int len)

+{

+    int i;

+    VirtIOPCIRegion *reg;

+

+    for (i = 0; i < ARRAY_SIZE(proxy->regs); ++i) {

+        reg = &proxy->regs[i];

+        if (*off >= reg->offset &&

+            *off + len <= reg->offset + reg->size) {

+            *off -= reg->offset;

+            return &reg->mr;

+        }

+    }

+

+    return NULL;

+}

+

 /* Below are generic functions to do memcpy from/to an address space,

  * without byteswaps, with input validation.

  *

@@ -558,63 +576,72 @@ static const MemoryRegionOps virtio_pci_config_ops = {

  * Note: host pointer must be aligned.

  */

 static

-void virtio_address_space_write(AddressSpace *as, hwaddr addr,

+void virtio_address_space_write(VirtIOPCIProxy *proxy, hwaddr addr,

                                 const uint8_t *buf, int len)

 {

-    uint32_t val;

+    uint64_t val;

+    MemoryRegion *mr;

     /* address_space_* APIs assume an aligned address.

      * As address is under guest control, handle illegal values.

      */

     addr &= ~(len - 1);

+    mr = virtio_address_space_lookup(proxy, &addr, len);

+    if (!mr) {

+        return;

+    }

+

     /* Make sure caller aligned buf properly */

     assert(!(((uintptr_t)buf) & (len - 1)));

     switch (len) {

     case 1:

         val = pci_get_byte(buf);

-        address_space_stb(as, addr, val, MEMTXATTRS_UNSPECIFIED, NULL);

         break;

     case 2:

-        val = pci_get_word(buf);

-        address_space_stw_le(as, addr, val, MEMTXATTRS_UNSPECIFIED, NULL);

+        val = cpu_to_le16(pci_get_word(buf));

         break;

     case 4:

-        val = pci_get_long(buf);

-        address_space_stl_le(as, addr, val, MEMTXATTRS_UNSPECIFIED, NULL);

+        val = cpu_to_le32(pci_get_long(buf));

         break;

     default:

         /* As length is under guest control, handle illegal values. */

-        break;

+        return;

     }

+    memory_region_dispatch_write(mr, addr, val, len, MEMTXATTRS_UNSPECIFIED);

 }

 static void

-virtio_address_space_read(AddressSpace *as, hwaddr addr, uint8_t *buf, int len)

+virtio_address_space_read(VirtIOPCIProxy *proxy, hwaddr addr,

+                          uint8_t *buf, int len)

 {

-    uint32_t val;

+    uint64_t val;

+    MemoryRegion *mr;

     /* address_space_* APIs assume an aligned address.

      * As address is under guest control, handle illegal values.

      */

     addr &= ~(len - 1);

+    mr = virtio_address_space_lookup(proxy, &addr, len);

+    if (!mr) {

+        return;

+    }

+

     /* Make sure caller aligned buf properly */

     assert(!(((uintptr_t)buf) & (len - 1)));

+    memory_region_dispatch_read(mr, addr, &val, len, MEMTXATTRS_UNSPECIFIED);

     switch (len) {

     case 1:

-        val = address_space_ldub(as, addr, MEMTXATTRS_UNSPECIFIED, NULL);

         pci_set_byte(buf, val);

         break;

     case 2:

-        val = address_space_lduw_le(as, addr, MEMTXATTRS_UNSPECIFIED, NULL);

-        pci_set_word(buf, val);

+        pci_set_word(buf, le16_to_cpu(val));

         break;

     case 4:

-        val = address_space_ldl_le(as, addr, MEMTXATTRS_UNSPECIFIED, NULL);

-        pci_set_long(buf, val);

+        pci_set_long(buf, le32_to_cpu(val));

         break;

     default:

         /* As length is under guest control, handle illegal values. */

@@ -650,8 +677,7 @@ static void virtio_write_config(PCIDevice *pci_dev, uint32_t address,

         if (len == 1 || len == 2 || len == 4) {

             assert(len <= sizeof cfg->pci_cfg_data);

-            virtio_address_space_write(&proxy->modern_as, off,

-                                       cfg->pci_cfg_data, len);

+            virtio_address_space_write(proxy, off, cfg->pci_cfg_data, len);

         }

     }

 }

@@ -675,8 +701,7 @@ static uint32_t virtio_read_config(PCIDevice *pci_dev,

         if (len == 1 || len == 2 || len == 4) {

             assert(len <= sizeof cfg->pci_cfg_data);

-            virtio_address_space_read(&proxy->modern_as, off,

-                                      cfg->pci_cfg_data, len);

+            virtio_address_space_read(proxy, off, cfg->pci_cfg_data, len);

         }

     }

@@ -1783,15 +1808,6 @@ static void virtio_pci_realize(PCIDevice *pci_dev, Error **errp)

                        /* PCI BAR regions must be powers of 2 */

                        pow2ceil(proxy->notify.offset + proxy->notify.size));

-    memory_region_init_alias(&proxy->modern_cfg,

-                             OBJECT(proxy),

-                             "virtio-pci-cfg",

-                             &proxy->modern_bar,

-                             0,

-                             memory_region_size(&proxy->modern_bar));

-

-    address_space_init(&proxy->modern_as, &proxy->modern_cfg, "virtio-pci-cfg-as");

-

     if (proxy->disable_legacy == ON_OFF_AUTO_AUTO) {

         proxy->disable_legacy = pcie_port ? ON_OFF_AUTO_ON : ON_OFF_AUTO_OFF;

     }

@@ -1860,10 +1876,7 @@ static void virtio_pci_realize(PCIDevice *pci_dev, Error **errp)

 static void virtio_pci_exit(PCIDevice *pci_dev)

 {

-    VirtIOPCIProxy *proxy = VIRTIO_PCI(pci_dev);

-

     msix_uninit_exclusive_bar(pci_dev);

-    address_space_destroy(&proxy->modern_as);

 }

 static void virtio_pci_reset(DeviceState *qdev)

diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h

index 69f5959..12d3a90 100644

--- a/hw/virtio/virtio-pci.h

+++ b/hw/virtio/virtio-pci.h

@@ -155,15 +155,18 @@ typedef struct VirtIOPCIQueue {

 struct VirtIOPCIProxy {

     PCIDevice pci_dev;

     MemoryRegion bar;

-    VirtIOPCIRegion common;

-    VirtIOPCIRegion isr;

-    VirtIOPCIRegion device;

-    VirtIOPCIRegion notify;

-    VirtIOPCIRegion notify_pio;

+    union {

+        struct {

+            VirtIOPCIRegion common;

+            VirtIOPCIRegion isr;

+            VirtIOPCIRegion device;

+            VirtIOPCIRegion notify;

+            VirtIOPCIRegion notify_pio;

+        };

+        VirtIOPCIRegion regs[5];

+    };

     MemoryRegion modern_bar;

     MemoryRegion io_bar;

-    MemoryRegion modern_cfg;

-    AddressSpace modern_as;

     uint32_t legacy_io_bar_idx;

     uint32_t msix_bar_idx;

     uint32_t modern_io_bar_idx;

-- 

1.8.3.1