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Re: [Xen-devel] [PATCH v6 1/1] xen-hvm.c: Add support for Xen access to vmport



On 10/20/14 11:03, Stefano Stabellini wrote:
On Mon, 20 Oct 2014, Don Slutz wrote:
This adds synchronisation of the 6 vcpu registers (only 32bits of
them) that vmport.c needs between Xen and QEMU.

This is to avoid a 2nd and 3rd exchange between QEMU and Xen to
fetch and put these 6 vcpu registers used by the code in vmport.c
and vmmouse.c

The registers are passed in the new shared page provided by
HVM_PARAM_VMPORT_REGS_PFN.

Add new array to XenIOState that allows selection of current_cpu by
vcpu id.

Now pass XenIOState to handle_ioreq().

Add new routines regs_to_cpu(), regs_from_cpu(), and
handle_vmport_ioreq().

Signed-off-by: Don Slutz <dslutz@xxxxxxxxxxx>
Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
v6:
     Do we need a forward declaration?
       Nope. Drooped.
     Added Reviewed-by from Paul Durrant.

v5:
     vmware_ioreq_t struct is not really a request any more. Maybe
     vmware_regs_t?
       Renamed various parts from vmware_ioreq to vmware_regs.  Also
       HVM_PARAM_VMPORT_IOREQ_PFN to HVM_PARAM_VMPORT_REGS_PFN.
     cpu_by_ioreq_id name implies the array is indexed by an id
     carries in the ioreq.
       Renamed cpu_by_ioreq_id to cpu_by_vcpu_id.
     Is cpu_get_vmport_ioreq_from_shared_memory worth its own
     function?
       Moved in-line.
     I don't think you need the barrier anyway.
       Dropped the barrier.
     Oh, I now realize you mean the same theoretical rather than
     actual limit, in which case this can be a build time check
     anyway.
       Switch to build time check, move to a better place.
     You could avoid passing state to both of them by setting
     current_cpu here couldn't you?
       Yes, moved state usage to handle_vmport_ioreq().
     Error out if it fails with error != -ENOSYS.
       Done.

v4:
     Please try to get rid of the #ifdefs.
       Moved 2 #ifdefs into hw/xen/xen_common.h


  include/hw/xen/xen_common.h |  22 +++++++++
  xen-hvm.c                   | 108 ++++++++++++++++++++++++++++++++++++++++++--
  2 files changed, 125 insertions(+), 5 deletions(-)

diff --git a/include/hw/xen/xen_common.h b/include/hw/xen/xen_common.h
index 07731b9..42e3d77 100644
--- a/include/hw/xen/xen_common.h
+++ b/include/hw/xen/xen_common.h
@@ -164,4 +164,26 @@ void destroy_hvm_domain(bool reboot);
  /* shutdown/destroy current domain because of an error */
  void xen_shutdown_fatal_error(const char *fmt, ...) GCC_FMT_ATTR(1, 2);
+#ifdef HVM_PARAM_VMPORT_REGS_PFN
+static inline int xen_get_vmport_regs_pfn(XenXC xc, domid_t dom,
+                                          unsigned long *vmport_regs_pfn)
+{
+    return xc_get_hvm_param(xc, dom, HVM_PARAM_VMPORT_REGS_PFN,
+                            vmport_regs_pfn);
+}
+#else
+static inline int xen_get_vmport_regs_pfn(XenXC xc, domid_t dom,
+                                          unsigned long *vmport_regs_pfn)
+{
+    return -ENOSYS;
+}
+#endif
+
+#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
+/* Force a compilation error if condition is true */
+#define BUILD_BUG_ON(cond) ({ _Static_assert(!(cond), "!(" #cond ")"); })
+#else
+#define BUILD_BUG_ON(cond) ((void)sizeof(struct { int:-!!(cond); }))
+#endif
Use QEMU_BUILD_BUG_ON, please do not define your own. But aside from
this, it is OK for me.


Sigh, I looked for this and failed to find it.  Will switch.
v7 soon.

    -Don Slutz

  #endif /* QEMU_HW_XEN_COMMON_H */
diff --git a/xen-hvm.c b/xen-hvm.c
index 05e522c..7c6291a 100644
--- a/xen-hvm.c
+++ b/xen-hvm.c
@@ -41,6 +41,29 @@ static MemoryRegion *framebuffer;
  static bool xen_in_migration;
/* Compatibility with older version */
+
+/* This allows QEMU to build on a system that has Xen 4.5 or earlier
+ * installed.  This here (not in hw/xen/xen_common.h) because xen/hvm/ioreq.h
+ * needs to be included before this block and hw/xen/xen_common.h needs to
+ * be included before xen/hvm/ioreq.h
+ */
+#ifndef IOREQ_TYPE_VMWARE_PORT
+#define IOREQ_TYPE_VMWARE_PORT  3
+struct vmware_regs {
+    uint32_t esi;
+    uint32_t edi;
+    uint32_t ebx;
+    uint32_t ecx;
+    uint32_t edx;
+};
+typedef struct vmware_regs vmware_regs_t;
+
+struct shared_vmport_iopage {
+    struct vmware_regs vcpu_vmport_regs[1];
+};
+typedef struct shared_vmport_iopage shared_vmport_iopage_t;
+#endif
+
  #if __XEN_LATEST_INTERFACE_VERSION__ < 0x0003020a
  static inline uint32_t xen_vcpu_eport(shared_iopage_t *shared_page, int i)
  {
@@ -79,8 +102,10 @@ typedef struct XenPhysmap {
typedef struct XenIOState {
      shared_iopage_t *shared_page;
+    shared_vmport_iopage_t *shared_vmport_page;
      buffered_iopage_t *buffered_io_page;
      QEMUTimer *buffered_io_timer;
+    CPUState **cpu_by_vcpu_id;
      /* the evtchn port for polling the notification, */
      evtchn_port_t *ioreq_local_port;
      /* evtchn local port for buffered io */
@@ -773,7 +798,50 @@ static void cpu_ioreq_move(ioreq_t *req)
      }
  }
-static void handle_ioreq(ioreq_t *req)
+static void regs_to_cpu(vmware_regs_t *vmport_regs, ioreq_t *req)
+{
+    X86CPU *cpu;
+    CPUX86State *env;
+
+    cpu = X86_CPU(current_cpu);
+    env = &cpu->env;
+    env->regs[R_EAX] = req->data;
+    env->regs[R_EBX] = vmport_regs->ebx;
+    env->regs[R_ECX] = vmport_regs->ecx;
+    env->regs[R_EDX] = vmport_regs->edx;
+    env->regs[R_ESI] = vmport_regs->esi;
+    env->regs[R_EDI] = vmport_regs->edi;
+}
+
+static void regs_from_cpu(vmware_regs_t *vmport_regs)
+{
+    X86CPU *cpu = X86_CPU(current_cpu);
+    CPUX86State *env = &cpu->env;
+
+    vmport_regs->ebx = env->regs[R_EBX];
+    vmport_regs->ecx = env->regs[R_ECX];
+    vmport_regs->edx = env->regs[R_EDX];
+    vmport_regs->esi = env->regs[R_ESI];
+    vmport_regs->edi = env->regs[R_EDI];
+}
+
+static void handle_vmport_ioreq(XenIOState *state, ioreq_t *req)
+{
+    vmware_regs_t *vmport_regs;
+
+    assert(state->shared_vmport_page);
+    vmport_regs =
+        &state->shared_vmport_page->vcpu_vmport_regs[state->send_vcpu];
+    BUILD_BUG_ON(sizeof(*req) < sizeof(*vmport_regs));
QEMU_BUILD_BUG_ON


+    current_cpu = state->cpu_by_vcpu_id[state->send_vcpu];
+    regs_to_cpu(vmport_regs, req);
+    cpu_ioreq_pio(req);
+    regs_from_cpu(vmport_regs);
+    current_cpu = NULL;
+}
+
+static void handle_ioreq(XenIOState *state, ioreq_t *req)
  {
      if (!req->data_is_ptr && (req->dir == IOREQ_WRITE) &&
              (req->size < sizeof (target_ulong))) {
@@ -787,6 +855,9 @@ static void handle_ioreq(ioreq_t *req)
          case IOREQ_TYPE_COPY:
              cpu_ioreq_move(req);
              break;
+        case IOREQ_TYPE_VMWARE_PORT:
+            handle_vmport_ioreq(state, req);
+            break;
          case IOREQ_TYPE_TIMEOFFSET:
              break;
          case IOREQ_TYPE_INVALIDATE:
@@ -828,7 +899,7 @@ static int handle_buffered_iopage(XenIOState *state)
              req.data |= ((uint64_t)buf_req->data) << 32;
          }
- handle_ioreq(&req);
+        handle_ioreq(state, &req);
xen_mb();
          state->buffered_io_page->read_pointer += qw ? 2 : 1;
@@ -857,14 +928,16 @@ static void cpu_handle_ioreq(void *opaque)
handle_buffered_iopage(state);
      if (req) {
-        handle_ioreq(req);
+        handle_ioreq(state, req);
if (req->state != STATE_IOREQ_INPROCESS) {
              fprintf(stderr, "Badness in I/O request ... not in service?!: "
                      "%x, ptr: %x, port: %"PRIx64", "
-                    "data: %"PRIx64", count: %" FMT_ioreq_size ", size: %" 
FMT_ioreq_size "\n",
+                    "data: %"PRIx64", count: %" FMT_ioreq_size
+                    ", size: %" FMT_ioreq_size
+                    ", type: %"FMT_ioreq_size"\n",
                      req->state, req->data_is_ptr, req->addr,
-                    req->data, req->count, req->size);
+                    req->data, req->count, req->size, req->type);
              destroy_hvm_domain(false);
              return;
          }
@@ -904,6 +977,14 @@ static void xen_main_loop_prepare(XenIOState *state)
                                                   state);
if (evtchn_fd != -1) {
+        CPUState *cpu_state;
+
+        DPRINTF("%s: Init cpu_by_vcpu_id\n", __func__);
+        CPU_FOREACH(cpu_state) {
+            DPRINTF("%s: cpu_by_vcpu_id[%d]=%p\n",
+                    __func__, cpu_state->cpu_index, cpu_state);
+            state->cpu_by_vcpu_id[cpu_state->cpu_index] = cpu_state;
+        }
          qemu_set_fd_handler(evtchn_fd, cpu_handle_ioreq, NULL, state);
      }
  }
@@ -1020,6 +1101,20 @@ int xen_hvm_init(ram_addr_t *below_4g_mem_size, 
ram_addr_t *above_4g_mem_size,
                   errno, xen_xc);
      }
+ rc = xen_get_vmport_regs_pfn(xen_xc, xen_domid, &ioreq_pfn);
+    if (!rc) {
+        DPRINTF("shared vmport page at pfn %lx\n", ioreq_pfn);
+        state->shared_vmport_page =
+            xc_map_foreign_range(xen_xc, xen_domid, XC_PAGE_SIZE,
+                                 PROT_READ|PROT_WRITE, ioreq_pfn);
+        if (state->shared_vmport_page == NULL) {
+            hw_error("map shared vmport IO page returned error %d handle="
+                     XC_INTERFACE_FMT, errno, xen_xc);
+        }
+    } else if (rc != -ENOSYS) {
+        hw_error("get vmport regs pfn returned error %d, rc=%d", errno, rc);
+    }
+
      xc_get_hvm_param(xen_xc, xen_domid, HVM_PARAM_BUFIOREQ_PFN, &ioreq_pfn);
      DPRINTF("buffered io page at pfn %lx\n", ioreq_pfn);
      state->buffered_io_page = xc_map_foreign_range(xen_xc, xen_domid, 
XC_PAGE_SIZE,
@@ -1028,6 +1123,9 @@ int xen_hvm_init(ram_addr_t *below_4g_mem_size, 
ram_addr_t *above_4g_mem_size,
          hw_error("map buffered IO page returned error %d", errno);
      }
+ /* Note: cpus is empty at this point in init */
+    state->cpu_by_vcpu_id = g_malloc0(max_cpus * sizeof(CPUState *));
+
      state->ioreq_local_port = g_malloc0(max_cpus * sizeof (evtchn_port_t));
/* FIXME: how about if we overflow the page here? */
--
1.8.4



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