[PATCH v10 12/19] multi-process: Forward PCI config space acceses to the remote process

From: elena.ufimtseva@oracle.com
To: qemu-devel@nongnu.org
Cc: elena.ufimtseva@oracle.com, fam@euphon.net,
	swapnil.ingle@nutanix.com, john.g.johnson@oracle.com,
	kraxel@redhat.com, jag.raman@oracle.com, quintela@redhat.com,
	mst@redhat.com, armbru@redhat.com, kanth.ghatraju@oracle.com,
	felipe@nutanix.com, thuth@redhat.com, ehabkost@redhat.com,
	konrad.wilk@oracle.com, dgilbert@redhat.com, stefanha@redhat.com,
	thanos.makatos@nutanix.com, rth@twiddle.net, kwolf@redhat.com,
	berrange@redhat.com, mreitz@redhat.com,
	ross.lagerwall@citrix.com, marcandre.lureau@gmail.com,
	pbonzini@redhat.com
Subject: [PATCH v10 12/19] multi-process: Forward PCI config space acceses to the remote process
Date: Mon,  5 Oct 2020 11:51:00 -0700	[thread overview]
Message-ID: <fc7a3b03ab53f317b2bb012362fcd7ed0b07f4ac.1601923020.git.elena.ufimtseva@oracle.com> (raw)
In-Reply-To: <cover.1601923020.git.elena.ufimtseva@oracle.com>

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 6451b77ae2..94937db1c5 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 6b954f22a5..083ec8382a 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)
 {
@@ -65,6 +67,51 @@ static void pci_proxy_dev_exit(PCIDevice *pdev)
     qio_channel_close(dev->ioc, NULL);
 }
 
+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);
@@ -72,6 +119,9 @@ 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 4bea5daeb4..459d345897 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 618061753b..4e0f57a7f5 100644
--- a/io/mpqemu-link.c
+++ b/io/mpqemu-link.c
@@ -271,6 +271,12 @@ 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;
     }
-- 
2.25.GIT


