[PATCH v11 12/19] multi-process: Forward PCI config space acceses to the remote process

[Jagannathan Raman]

From: Elena Ufimtseva <elena.ufimtseva@oracle.com>

The Proxy Object sends the PCI config space accesses as messages
to the remote process over the communication channel

TODO:
Investigate if the local PCI config writes can be dropped.
Without the proxy local PCI config space writes for the device,
the driver in the guest times out on the probing.
We have tried to only refer to the remote for the PCI config writes,
but the driver timeout in the guest forced as to left this
as it is (removing local PCI config only).

Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 hw/i386/remote-msg.c     | 62 ++++++++++++++++++++++++++++++++++++++++++++++++
 hw/pci/proxy.c           | 50 ++++++++++++++++++++++++++++++++++++++
 include/io/mpqemu-link.h |  9 +++++++
 io/mpqemu-link.c         |  6 +++++
 4 files changed, 127 insertions(+)

diff --git a/hw/i386/remote-msg.c b/hw/i386/remote-msg.c
index 6451b77..94937db 100644
--- a/hw/i386/remote-msg.c
+++ b/hw/i386/remote-msg.c
@@ -15,6 +15,12 @@
 #include "io/mpqemu-link.h"
 #include "qapi/error.h"
 #include "sysemu/runstate.h"
+#include "hw/pci/pci.h"
+
+static void process_config_write(QIOChannel *ioc, PCIDevice *dev,
+                                 MPQemuMsg *msg);
+static void process_config_read(QIOChannel *ioc, PCIDevice *dev,
+                                MPQemuMsg *msg);
 
 void coroutine_fn mpqemu_remote_msg_loop_co(void *data)
 {
@@ -43,6 +49,12 @@ void coroutine_fn mpqemu_remote_msg_loop_co(void *data)
         }
 
         switch (msg.cmd) {
+        case PCI_CONFIG_WRITE:
+            process_config_write(com->ioc, pci_dev, &msg);
+            break;
+        case PCI_CONFIG_READ:
+            process_config_read(com->ioc, pci_dev, &msg);
+            break;
         default:
             error_setg(&local_err,
                        "Unknown command (%d) received for device %s (pid=%d)",
@@ -60,3 +72,53 @@ void coroutine_fn mpqemu_remote_msg_loop_co(void *data)
 
     return;
 }
+
+static void process_config_write(QIOChannel *ioc, PCIDevice *dev,
+                                 MPQemuMsg *msg)
+{
+    ConfDataMsg *conf = (ConfDataMsg *)&msg->data.conf_data;
+    MPQemuMsg ret = { 0 };
+    Error *local_err = NULL;
+
+    if ((conf->addr + sizeof(conf->val)) > pci_config_size(dev)) {
+        error_report("Bad address received when writing PCI config, pid %d",
+                     getpid());
+        ret.data.u64 = UINT64_MAX;
+    } else {
+        pci_default_write_config(dev, conf->addr, conf->val, conf->l);
+    }
+
+    ret.cmd = RET_MSG;
+    ret.size = sizeof(ret.data.u64);
+
+    mpqemu_msg_send(&ret, ioc, &local_err);
+    if (local_err) {
+        error_report("Could not send message to proxy from pid %d",
+                     getpid());
+    }
+}
+
+static void process_config_read(QIOChannel *ioc, PCIDevice *dev,
+                                MPQemuMsg *msg)
+{
+    ConfDataMsg *conf = (ConfDataMsg *)&msg->data.conf_data;
+    MPQemuMsg ret = { 0 };
+    Error *local_err = NULL;
+
+    if ((conf->addr + sizeof(conf->val)) > pci_config_size(dev)) {
+        error_report("Bad address received when reading PCI config, pid %d",
+                     getpid());
+        ret.data.u64 = UINT64_MAX;
+    } else {
+        ret.data.u64 = pci_default_read_config(dev, conf->addr, conf->l);
+    }
+
+    ret.cmd = RET_MSG;
+    ret.size = sizeof(ret.data.u64);
+
+    mpqemu_msg_send(&ret, ioc, &local_err);
+    if (local_err) {
+        error_report("Could not send message to proxy from pid %d",
+                     getpid());
+    }
+}
diff --git a/hw/pci/proxy.c b/hw/pci/proxy.c
index 7a12f23..27714fe 100644
--- a/hw/pci/proxy.c
+++ b/hw/pci/proxy.c
@@ -16,6 +16,8 @@
 #include "hw/qdev-properties.h"
 #include "monitor/monitor.h"
 #include "migration/blocker.h"
+#include "io/mpqemu-link.h"
+#include "qemu/error-report.h"
 
 static void proxy_set_socket(PCIProxyDev *pdev, int fd, Error **errp)
 {
@@ -69,6 +71,51 @@ static void pci_proxy_dev_exit(PCIDevice *pdev)
     error_free(dev->migration_blocker);
 }
 
+static int config_op_send(PCIProxyDev *pdev, uint32_t addr, uint32_t *val,
+                          int l, unsigned int op)
+{
+    MPQemuMsg msg = { 0 };
+    uint64_t ret = -EINVAL;
+    Error *local_err = NULL;
+
+    msg.cmd = op;
+    msg.data.conf_data.addr = addr;
+    msg.data.conf_data.val = (op == PCI_CONFIG_WRITE) ? *val : 0;
+    msg.data.conf_data.l = l;
+    msg.size = sizeof(ConfDataMsg);
+
+    ret = mpqemu_msg_send_and_await_reply(&msg, pdev, &local_err);
+    if (local_err) {
+        error_report_err(local_err);
+    }
+    if (op == PCI_CONFIG_READ) {
+        *val = (uint32_t)ret;
+    }
+
+    return ret;
+}
+
+static uint32_t pci_proxy_read_config(PCIDevice *d, uint32_t addr, int len)
+{
+    uint32_t val;
+
+    (void)config_op_send(PCI_PROXY_DEV(d), addr, &val, len, PCI_CONFIG_READ);
+
+    return val;
+}
+
+static void pci_proxy_write_config(PCIDevice *d, uint32_t addr, uint32_t val,
+                                   int l)
+{
+    /*
+     * Some of the functions access the copy of the remote device
+     * PCI config space, therefore maintain it updated.
+     */
+    pci_default_write_config(d, addr, val, l);
+
+    (void)config_op_send(PCI_PROXY_DEV(d), addr, &val, l, PCI_CONFIG_WRITE);
+}
+
 static void pci_proxy_dev_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
@@ -76,6 +123,9 @@ static void pci_proxy_dev_class_init(ObjectClass *klass, 
void *data)
 
     k->realize = pci_proxy_dev_realize;
     k->exit = pci_proxy_dev_exit;
+    k->config_read = pci_proxy_read_config;
+    k->config_write = pci_proxy_write_config;
+
     device_class_set_props(dc, proxy_properties);
 }
 
diff --git a/include/io/mpqemu-link.h b/include/io/mpqemu-link.h
index 4bea5da..459d345 100644
--- a/include/io/mpqemu-link.h
+++ b/include/io/mpqemu-link.h
@@ -34,6 +34,8 @@ typedef enum {
     MPQEMU_CMD_INIT,
     SYNC_SYSMEM,
     RET_MSG,
+    PCI_CONFIG_WRITE,
+    PCI_CONFIG_READ,
     MPQEMU_CMD_MAX,
 } MPQemuCmd;
 
@@ -43,6 +45,12 @@ typedef struct {
     off_t offsets[REMOTE_MAX_FDS];
 } SyncSysmemMsg;
 
+typedef struct {
+    uint32_t addr;
+    uint32_t val;
+    int l;
+} ConfDataMsg;
+
 /**
  * MPQemuMsg:
  * @cmd: The remote command
@@ -60,6 +68,7 @@ typedef struct {
 
     union {
         uint64_t u64;
+        ConfDataMsg conf_data;
         SyncSysmemMsg sync_sysmem;
     } data;
 
diff --git a/io/mpqemu-link.c b/io/mpqemu-link.c
index 1339cc7..5ef82da 100644
--- a/io/mpqemu-link.c
+++ b/io/mpqemu-link.c
@@ -278,6 +278,12 @@ bool mpqemu_msg_valid(MPQemuMsg *msg)
             return false;
         }
         break;
+    case PCI_CONFIG_WRITE:
+    case PCI_CONFIG_READ:
+        if (msg->size != sizeof(ConfDataMsg)) {
+            return false;
+        }
+        break;
     default:
         break;
     }
-- 
1.8.3.1