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Re: [Xen-devel] [PATCH v2 1/1] xen-hvm.c: Add support for Xen access to vmport



On 10/03/14 05:52, Stefano Stabellini wrote:
On Thu, 2 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

Add new array to XenIOState that allows selection of current_cpu by
ioreq_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>
---
v2:
    More info in commit message.
        Added vmware_ioreq_t
       Added cpu_by_ioreq_id.
       Set current_cpu in regs_to_cpu(), clear in regs_from_cpu().
       Drop all changes to vmport.c

  xen-hvm.c | 152 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-------
  1 file changed, 137 insertions(+), 15 deletions(-)

diff --git a/xen-hvm.c b/xen-hvm.c
index 05e522c..d80f21c 100644
--- a/xen-hvm.c
+++ b/xen-hvm.c
@@ -41,6 +41,31 @@ 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_ioreq {
+        uint32_t esi;
+        uint32_t edi;
+        uint32_t eax;
+        uint32_t ebx;
+        uint32_t ecx;
+        uint32_t edx;
+        uint32_t vp_eport; /* evtchn for notifications to/from device model */
+        uint16_t addr;
+        uint8_t  state:4;
+        uint8_t  dir:1;    /* 1=read, 0=write */
+        uint8_t  size:3;
+        uint8_t  type;     /* I/O type */
+};
+typedef struct vmware_ioreq vmware_ioreq_t;
+#endif
Why here instead of include/hw/xen/xen_common.h?


See code comment above.  Copied here just to make sure.


+
+/* 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
+ */



  #if __XEN_LATEST_INTERFACE_VERSION__ < 0x0003020a
  static inline uint32_t xen_vcpu_eport(shared_iopage_t *shared_page, int i)
  {
@@ -81,6 +106,7 @@ typedef struct XenIOState {
      shared_iopage_t *shared_page;
      buffered_iopage_t *buffered_io_page;
      QEMUTimer *buffered_io_timer;
+    CPUState **cpu_by_ioreq_id;
      /* the evtchn port for polling the notification, */
      evtchn_port_t *ioreq_local_port;
      /* evtchn local port for buffered io */
@@ -101,6 +127,8 @@ typedef struct XenIOState {
      Notifier wakeup;
  } XenIOState;
+static void handle_ioreq(XenIOState *state, ioreq_t *req);
+
  /* Xen specific function for piix pci */
int xen_pci_slot_get_pirq(PCIDevice *pci_dev, int irq_num)
@@ -596,11 +624,23 @@ static ioreq_t 
*cpu_get_ioreq_from_shared_memory(XenIOState *state, int vcpu)
      ioreq_t *req = xen_vcpu_ioreq(state->shared_page, vcpu);
if (req->state != STATE_IOREQ_READY) {
-        DPRINTF("I/O request not ready: "
-                "%x, ptr: %x, port: %"PRIx64", "
-                "data: %"PRIx64", count: %" FMT_ioreq_size ", size: %" FMT_ioreq_size 
"\n",
-                req->state, req->data_is_ptr, req->addr,
-                req->data, req->count, req->size);
+        if (req->type != IOREQ_TYPE_VMWARE_PORT) {
+            DPRINTF("I/O request not ready: "
+                    "%x, ptr: %x, port: %"PRIx64", "
+                    "data: %"PRIx64", count: %" FMT_ioreq_size ", size: %"
+                    FMT_ioreq_size "\n",
+                    req->state, req->data_is_ptr, req->addr,
+                    req->data, req->count, req->size);
+        } else {
+#ifdef DEBUG_XEN_HVM
+            vmware_ioreq_t *vp = (vmware_ioreq_t *)req;
+            DPRINTF("I/O VMware request not ready: "
+                    "%x, ptr: 0, port: %x, data: %x"
+                    ", count: 1, size: %d\n",
+                    vp->state, (uint16_t)vp->edx, vp->eax,
+                    vp->size);
+#endif
+        }
          return NULL;
      }
@@ -773,10 +813,73 @@ static void cpu_ioreq_move(ioreq_t *req)
      }
  }
-static void handle_ioreq(ioreq_t *req)
+static void regs_to_cpu(XenIOState *state, vmware_ioreq_t *vmport_req)
+{
+    X86CPU *cpu;
+    CPUX86State *env;
+
+    if (!state->cpu_by_ioreq_id[0]) {
+        CPUState *cpu_state;
+
+        CPU_FOREACH(cpu_state) {
+            state->cpu_by_ioreq_id[cpu_state->cpu_index] = cpu_state;
+        }
+    }
This is just the initialization, isn't it?
It would be best to move it to an initialization function then.


A new initialization function would need to be added. A new call to it would need
to be added (not sure where the best place is).  Since the overhead here is
small I went with the less intrusive change.

+    current_cpu = state->cpu_by_ioreq_id[state->send_vcpu];
+    cpu = X86_CPU(current_cpu);
+    env = &cpu->env;
+    env->regs[R_EAX] = vmport_req->eax;
+    env->regs[R_EBX] = vmport_req->ebx;
+    env->regs[R_ECX] = vmport_req->ecx;
+    env->regs[R_EDX] = vmport_req->edx;
+    env->regs[R_ESI] = vmport_req->esi;
+    env->regs[R_EDI] = vmport_req->edi;
+}
+
+static void regs_from_cpu(XenIOState *state, vmware_ioreq_t *vmport_req,
+                          ioreq_t *req)
+{
+    X86CPU *cpu = X86_CPU(current_cpu);
+    CPUX86State *env = &cpu->env;
+
+    assert(sizeof(*vmport_req) == sizeof(*req));
+    assert(offsetof(ioreq_t, type) == offsetof(vmware_ioreq_t, type));
+    assert(offsetof(ioreq_t, vp_eport) == offsetof(vmware_ioreq_t, vp_eport));
+
+    vmport_req->eax = env->regs[R_EAX];
+    vmport_req->ebx = env->regs[R_EBX];
+    vmport_req->ecx = env->regs[R_ECX];
+    vmport_req->edx = env->regs[R_EDX];
+    vmport_req->esi = env->regs[R_ESI];
+    vmport_req->edi = env->regs[R_EDI];
+    current_cpu = NULL;
+}
+
+static void handle_vmport_ioreq(XenIOState *state, vmware_ioreq_t *vmport_req)
+{
+    ioreq_t req;
+
+    memset(&req, 0x00, sizeof(req));
+
+    req.size = vmport_req->size;
+    req.count = 1;
+    req.addr = vmport_req->addr;
+    req.data = vmport_req->eax;
+    req.state = STATE_IOREQ_READY;
+    req.dir = vmport_req->dir;
+    req.df = 0;
+    req.type = IOREQ_TYPE_PIO;
+    req.data_is_ptr = 0;
+
+    regs_to_cpu(state, vmport_req);
+    handle_ioreq(state, &req);
+    regs_from_cpu(state, vmport_req, &req);
+}
I think that this is far better than the previous version

Good.

   -Don Slutz



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