[Qemu-devel] [PATCH v4] xen-hvm: stop faking I/O to access PCI config space

[Qemu-devel] [PATCH v4] xen-hvm: stop faking I/O to access PCI config space

[Paul Durrant]

This patch removes the current hackery where IOREQ_TYPE_PCI_CONFIG
requests are handled by faking PIO to 0xcf8 and 0xcfc and replaces it
with direct calls to pci_host_config_read/write_common().
Doing so necessitates mapping BDFs to PCIDevices but maintaining a simple
QLIST in xen_device_realize/unrealize() will suffice.

NOTE: whilst config space accesses are currently limited to
      PCI_CONFIG_SPACE_SIZE, this patch paves the way to increasing the
      limit to PCIE_CONFIG_SPACE_SIZE when Xen gains the ability to
      emulate MCFG table accesses.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
--
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Marcel Apfelbaum <marcel@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Roger Pau Monne <roger.pau@citrix.com>
Cc: Jan Beulich <JBeulich@suse.com>

v4:
 - Fix compile error

v3:
 - Drop helper function and treat count > 1 as an error
 - Add Jan to cc list

v2:
 - Introduce a helper function rw_config_req_item() to handle config
   register offset calculation
 - Handle req->count > 1 more like MMIO rather than PIO
 - Add Roger to cc list (not taking R-b because of significant change)
---
 hw/i386/xen/trace-events |   2 +
 hw/i386/xen/xen-hvm.c    | 102 +++++++++++++++++++++++++++++++++++++----------
 2 files changed, 84 insertions(+), 20 deletions(-)

diff --git a/hw/i386/xen/trace-events b/hw/i386/xen/trace-events
index 8dab7bc..f576f1b 100644
--- a/hw/i386/xen/trace-events
+++ b/hw/i386/xen/trace-events
@@ -15,6 +15,8 @@ cpu_ioreq_pio(void *req, uint32_t dir, uint32_t df, uint32_t data_is_ptr, uint64
 cpu_ioreq_pio_read_reg(void *req, uint64_t data, uint64_t addr, uint32_t size) "I/O=%p pio read reg data=0x%"PRIx64" port=0x%"PRIx64" size=%d"
 cpu_ioreq_pio_write_reg(void *req, uint64_t data, uint64_t addr, uint32_t size) "I/O=%p pio write reg data=0x%"PRIx64" port=0x%"PRIx64" size=%d"
 cpu_ioreq_move(void *req, uint32_t dir, uint32_t df, uint32_t data_is_ptr, uint64_t addr, uint64_t data, uint32_t count, uint32_t size) "I/O=%p copy dir=%d df=%d ptr=%d port=0x%"PRIx64" data=0x%"PRIx64" count=%d size=%d"
+cpu_ioreq_config_read(void *req, uint32_t sbdf, uint32_t reg, uint32_t size, uint32_t data) "I/O=%p sbdf=0x%x reg=%u size=%u data=0x%x"
+cpu_ioreq_config_write(void *req, uint32_t sbdf, uint32_t reg, uint32_t size, uint32_t data) "I/O=%p sbdf=0x%x reg=%u size=%u data=0x%x"
 
 # xen-mapcache.c
 xen_map_cache(uint64_t phys_addr) "want 0x%"PRIx64
diff --git a/hw/i386/xen/xen-hvm.c b/hw/i386/xen/xen-hvm.c
index caa563b..af4ff460 100644
--- a/hw/i386/xen/xen-hvm.c
+++ b/hw/i386/xen/xen-hvm.c
@@ -12,6 +12,7 @@
 
 #include "cpu.h"
 #include "hw/pci/pci.h"
+#include "hw/pci/pci_host.h"
 #include "hw/i386/pc.h"
 #include "hw/i386/apic-msidef.h"
 #include "hw/xen/xen_common.h"
@@ -86,6 +87,12 @@ typedef struct XenPhysmap {
     QLIST_ENTRY(XenPhysmap) list;
 } XenPhysmap;
 
+typedef struct XenPciDevice {
+    PCIDevice *pci_dev;
+    uint32_t sbdf;
+    QLIST_ENTRY(XenPciDevice) entry;
+} XenPciDevice;
+
 typedef struct XenIOState {
     ioservid_t ioservid;
     shared_iopage_t *shared_page;
@@ -105,6 +112,7 @@ typedef struct XenIOState {
     struct xs_handle *xenstore;
     MemoryListener memory_listener;
     MemoryListener io_listener;
+    QLIST_HEAD(, XenPciDevice) dev_list;
     DeviceListener device_listener;
     QLIST_HEAD(, XenPhysmap) physmap;
     hwaddr free_phys_offset;
@@ -569,6 +577,12 @@ static void xen_device_realize(DeviceListener *listener,
 
     if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
         PCIDevice *pci_dev = PCI_DEVICE(dev);
+        XenPciDevice *xendev = g_new(XenPciDevice, 1);
+
+        xendev->pci_dev = pci_dev;
+        xendev->sbdf = PCI_BUILD_BDF(pci_dev_bus_num(pci_dev),
+                                     pci_dev->devfn);
+        QLIST_INSERT_HEAD(&state->dev_list, xendev, entry);
 
         xen_map_pcidev(xen_domid, state->ioservid, pci_dev);
     }
@@ -581,8 +595,17 @@ static void xen_device_unrealize(DeviceListener *listener,
 
     if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
         PCIDevice *pci_dev = PCI_DEVICE(dev);
+        XenPciDevice *xendev, *next;
 
         xen_unmap_pcidev(xen_domid, state->ioservid, pci_dev);
+
+        QLIST_FOREACH_SAFE(xendev, &state->dev_list, entry, next) {
+            if (xendev->pci_dev == pci_dev) {
+                QLIST_REMOVE(xendev, entry);
+                g_free(xendev);
+                break;
+            }
+        }
     }
 }
 
@@ -903,6 +926,62 @@ static void cpu_ioreq_move(ioreq_t *req)
     }
 }
 
+static void cpu_ioreq_config(XenIOState *state, ioreq_t *req)
+{
+    uint32_t sbdf = req->addr >> 32;
+    uint32_t reg = req->addr;
+    XenPciDevice *xendev;
+
+    if (req->size != sizeof(uint8_t) && req->size != sizeof(uint16_t) &&
+        req->size != sizeof(uint32_t)) {
+        hw_error("PCI config access: bad size (%u)", req->size);
+    }
+
+    if (req->count != 1) {
+        hw_error("PCI config access: bad count (%u)", req->count);
+    }
+
+    QLIST_FOREACH(xendev, &state->dev_list, entry) {
+        if (xendev->sbdf != sbdf) {
+            continue;
+        }
+
+        if (!req->data_is_ptr) {
+            if (req->dir == IOREQ_READ) {
+                req->data = pci_host_config_read_common(
+                    xendev->pci_dev, reg, PCI_CONFIG_SPACE_SIZE,
+                    req->size);
+                trace_cpu_ioreq_config_read(req, xendev->sbdf, reg,
+                                            req->size, req->data);
+            } else if (req->dir == IOREQ_WRITE) {
+                trace_cpu_ioreq_config_write(req, xendev->sbdf, reg,
+                                             req->size, req->data);
+                pci_host_config_write_common(
+                    xendev->pci_dev, reg, PCI_CONFIG_SPACE_SIZE,
+                    req->data, req->size);
+            }
+        } else {
+            uint32_t tmp;
+
+            if (req->dir == IOREQ_READ) {
+                tmp = pci_host_config_read_common(
+                    xendev->pci_dev, reg, PCI_CONFIG_SPACE_SIZE,
+                    req->size);
+                trace_cpu_ioreq_config_read(req, xendev->sbdf, reg,
+                                            req->size, tmp);
+                write_phys_req_item(req->data, req, 0, &tmp);
+            } else if (req->dir == IOREQ_WRITE) {
+                read_phys_req_item(req->data, req, 0, &tmp);
+                trace_cpu_ioreq_config_write(req, xendev->sbdf, reg,
+                                             req->size, tmp);
+                pci_host_config_write_common(
+                    xendev->pci_dev, reg, PCI_CONFIG_SPACE_SIZE,
+                    tmp, req->size);
+            }
+        }
+    }
+}
+
 static void regs_to_cpu(vmware_regs_t *vmport_regs, ioreq_t *req)
 {
     X86CPU *cpu;
@@ -975,27 +1054,9 @@ static void handle_ioreq(XenIOState *state, ioreq_t *req)
         case IOREQ_TYPE_INVALIDATE:
             xen_invalidate_map_cache();
             break;
-        case IOREQ_TYPE_PCI_CONFIG: {
-            uint32_t sbdf = req->addr >> 32;
-            uint32_t val;
-
-            /* Fake a write to port 0xCF8 so that
-             * the config space access will target the
-             * correct device model.
-             */
-            val = (1u << 31) |
-                  ((req->addr & 0x0f00) << 16) |
-                  ((sbdf & 0xffff) << 8) |
-                  (req->addr & 0xfc);
-            do_outp(0xcf8, 4, val);
-
-            /* Now issue the config space access via
-             * port 0xCFC
-             */
-            req->addr = 0xcfc | (req->addr & 0x03);
-            cpu_ioreq_pio(req);
+        case IOREQ_TYPE_PCI_CONFIG:
+            cpu_ioreq_config(state, req);
             break;
-        }
         default:
             hw_error("Invalid ioreq type 0x%x\n", req->type);
     }
@@ -1366,6 +1427,7 @@ void xen_hvm_init(PCMachineState *pcms, MemoryRegion **ram_memory)
     memory_listener_register(&state->io_listener, &address_space_io);
 
     state->device_listener = xen_device_listener;
+    QLIST_INIT(&state->dev_list);
     device_listener_register(&state->device_listener);
 
     /* Initialize backend core & drivers */
-- 
2.1.4

Re: [Qemu-devel] [PATCH v4] xen-hvm: stop faking I/O to access PCI config space

[Anthony PERARD]

On Fri, May 18, 2018 at 03:38:30PM +0100, Paul Durrant wrote:
> This patch removes the current hackery where IOREQ_TYPE_PCI_CONFIG
> requests are handled by faking PIO to 0xcf8 and 0xcfc and replaces it
> with direct calls to pci_host_config_read/write_common().
> Doing so necessitates mapping BDFs to PCIDevices but maintaining a simple
> QLIST in xen_device_realize/unrealize() will suffice.
> 
> NOTE: whilst config space accesses are currently limited to
>       PCI_CONFIG_SPACE_SIZE, this patch paves the way to increasing the
>       limit to PCIE_CONFIG_SPACE_SIZE when Xen gains the ability to
>       emulate MCFG table accesses.
> 
> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>

Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>

-- 
Anthony PERARD