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[Xen-devel] [RFC][PATCH v2x prototype 1/1] xen-hvm.c: Add support for Xen access to vmport



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>
---
As requested by Paul Durrant <Paul.Durrant@xxxxxxxxxx>

Here is a prototype of the QEMU change using a 2nd shared page.
I picked adding HVM_PARAM_VMPORT_IOREQ_PFN as the simple and
fast way to handle QEMU building on older Xen versions.


 xen-hvm.c | 128 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 123 insertions(+), 5 deletions(-)

diff --git a/xen-hvm.c b/xen-hvm.c
index 05e522c..5e80159 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_ioreq {
+    uint32_t esi;
+    uint32_t edi;
+    uint32_t ebx;
+    uint32_t ecx;
+    uint32_t edx;
+};
+typedef struct vmware_ioreq vmware_ioreq_t;
+
+struct shared_vmport_iopage {
+    struct vmware_ioreq vcpu_vmport_ioreq[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_ioreq_id;
     /* the evtchn port for polling the notification, */
     evtchn_port_t *ioreq_local_port;
     /* evtchn local port for buffered io */
@@ -101,6 +126,8 @@ 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)
@@ -610,6 +637,20 @@ static ioreq_t 
*cpu_get_ioreq_from_shared_memory(XenIOState *state, int vcpu)
     return req;
 }
 
+/* get the vmport ioreq packets from share mem */
+static vmware_ioreq_t *cpu_get_vmport_ioreq_from_shared_memory(
+    XenIOState *state, int vcpu)
+{
+    vmware_ioreq_t *vmport_req;
+
+    assert(state->shared_vmport_page);
+    vmport_req = &state->shared_vmport_page->vcpu_vmport_ioreq[vcpu];
+
+    xen_rmb(); /* see IOREQ_READY /then/ read contents of ioreq */
+
+    return vmport_req;
+}
+
 /* use poll to get the port notification */
 /* ioreq_vec--out,the */
 /* retval--the number of ioreq packet */
@@ -773,7 +814,51 @@ 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,
+                        ioreq_t *req)
+{
+    X86CPU *cpu;
+    CPUX86State *env;
+
+    current_cpu = state->cpu_by_ioreq_id[state->send_vcpu];
+    cpu = X86_CPU(current_cpu);
+    env = &cpu->env;
+    env->regs[R_EAX] = req->data;
+    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));
+
+    req->data = 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, ioreq_t *req)
+{
+    vmware_ioreq_t *vmport_req =
+        cpu_get_vmport_ioreq_from_shared_memory(state, state->send_vcpu);
+
+    regs_to_cpu(state, vmport_req, req);
+    cpu_ioreq_pio(req);
+    regs_from_cpu(state, vmport_req, req);
+}
+
+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 +872,9 @@ 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 +916,7 @@ 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 +945,16 @@ 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 +994,14 @@ static void xen_main_loop_prepare(XenIOState *state)
                                                  state);
 
     if (evtchn_fd != -1) {
+        CPUState *cpu_state;
+
+        fprintf(stderr, "%s: Init cpu_by_ioreq_id\n", __func__);
+        CPU_FOREACH(cpu_state) {
+            fprintf(stderr, "%s: cpu_by_ioreq_id[%d]=%p\n",
+                    __func__, cpu_state->cpu_index, cpu_state);
+            state->cpu_by_ioreq_id[cpu_state->cpu_index] = cpu_state;
+        }
         qemu_set_fd_handler(evtchn_fd, cpu_handle_ioreq, NULL, state);
     }
 }
@@ -987,6 +1085,9 @@ int xen_hvm_init(ram_addr_t *below_4g_mem_size, ram_addr_t 
*above_4g_mem_size,
     unsigned long ioreq_pfn;
     unsigned long bufioreq_evtchn;
     XenIOState *state;
+#ifdef HVM_PARAM_VMPORT_IOREQ_PFN
+    unsigned long vmport_ioreq_pfn;
+#endif
 
     state = g_malloc0(sizeof (XenIOState));
 
@@ -1020,6 +1121,20 @@ int xen_hvm_init(ram_addr_t *below_4g_mem_size, 
ram_addr_t *above_4g_mem_size,
                  errno, xen_xc);
     }
 
+#ifdef HVM_PARAM_VMPORT_IOREQ_PFN
+    xc_get_hvm_param(xen_xc, xen_domid, HVM_PARAM_VMPORT_IOREQ_PFN,
+                     &vmport_ioreq_pfn);
+    DPRINTF("shared vmport page at pfn %lx\n", vmport_ioreq_pfn);
+    state->shared_vmport_page = xc_map_foreign_range(xen_xc, xen_domid,
+                                                     XC_PAGE_SIZE,
+                                                     PROT_READ|PROT_WRITE,
+                                                     vmport_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);
+    }
+#endif
+
     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 +1143,9 @@ 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_ioreq_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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