[PATCH v6 10/16] x86/hvm: only call hvm_io_assist() from hvm_wait_for_io()

[Paul Durrant <paul.durrant@citrix.com>]

By removing the calls in hvmemul_do_io() (which is replaced by a single
assignment) and hvm_complete_assist_request() (which is replaced by a
call to hvm_process_portio_intercept() with a suitable set of ops) then
hvm_io_assist() can be moved into hvm.c and made static (and hence be a
candidate for inlining).

The calls to msix_write_completion() and vcpu_end_shutdown_deferral()
are also made unconditionally because the ioreq state will always be
STATE_IOREQ_NONE at the end of hvm_io_assist() so the test was
pointless. These calls are also only relevant when the emulation has
been handled externally which is now always the case.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Keir Fraser <keir@xen.org>
Acked-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
 xen/arch/x86/hvm/emulate.c    |   34 ++++++++++++++++++---
 xen/arch/x86/hvm/hvm.c        |   67 ++++++++++++++++++++++-------------------
 xen/arch/x86/hvm/io.c         |   39 ------------------------
 xen/include/asm-x86/hvm/hvm.h |    1 -
 xen/include/asm-x86/hvm/io.h  |    1 -
 5 files changed, 66 insertions(+), 76 deletions(-)

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index c80c488..d1775ac 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -50,6 +50,32 @@ static void hvmtrace_io_assist(const ioreq_t *p)
     trace_var(event, 0/*!cycles*/, size, buffer);
 }
 
+static int null_read(const struct hvm_io_handler *io_handler,
+                     uint64_t addr,
+                     uint32_t size,
+                     uint64_t *data)
+{
+    *data = ~0ul;
+    return X86EMUL_OKAY;
+}
+
+static int null_write(const struct hvm_io_handler *handler,
+                      uint64_t addr,
+                      uint32_t size,
+                      uint64_t data)
+{
+    return X86EMUL_OKAY;
+}
+
+static const struct hvm_io_ops null_ops = {
+    .read = null_read,
+    .write = null_write
+};
+
+static const struct hvm_io_handler null_handler = {
+    .ops = &null_ops
+};
+
 static int hvmemul_do_io(
     bool_t is_mmio, paddr_t addr, unsigned long reps, unsigned int size,
     uint8_t dir, bool_t df, bool_t data_is_addr, uintptr_t data)
@@ -139,8 +165,7 @@ static int hvmemul_do_io(
     switch ( rc )
     {
     case X86EMUL_OKAY:
-        p.state = STATE_IORESP_READY;
-        hvm_io_assist(&p);
+        vio->io_data = p.data;
         vio->io_state = HVMIO_none;
         break;
     case X86EMUL_UNHANDLEABLE:
@@ -151,8 +176,9 @@ static int hvmemul_do_io(
         /* If there is no suitable backing DM, just ignore accesses */
         if ( !s )
         {
-            hvm_complete_assist_req(&p);
-            rc = X86EMUL_OKAY;
+            rc = hvm_process_io_intercept(&null_handler, &p);
+            if ( rc == X86EMUL_OKAY )
+                vio->io_data = p.data;
             vio->io_state = HVMIO_none;
         }
         else
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 810e579..c1a58c2 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -411,6 +411,42 @@ bool_t hvm_io_pending(struct vcpu *v)
     return 0;
 }
 
+static void hvm_io_assist(ioreq_t *p)
+{
+    struct vcpu *curr = current;
+    struct hvm_vcpu_io *vio = &curr->arch.hvm_vcpu.hvm_io;
+    enum hvm_io_state io_state;
+
+    p->state = STATE_IOREQ_NONE;
+
+    io_state = vio->io_state;
+    vio->io_state = HVMIO_none;
+
+    switch ( io_state )
+    {
+    case HVMIO_awaiting_completion:
+        vio->io_state = HVMIO_completed;
+        vio->io_data = p->data;
+        break;
+    case HVMIO_handle_mmio_awaiting_completion:
+        vio->io_state = HVMIO_completed;
+        vio->io_data = p->data;
+        (void)handle_mmio();
+        break;
+    case HVMIO_handle_pio_awaiting_completion:
+        if ( vio->io_size == 4 ) /* Needs zero extension. */
+            guest_cpu_user_regs()->rax = (uint32_t)p->data;
+        else
+            memcpy(&guest_cpu_user_regs()->rax, &p->data, vio->io_size);
+        break;
+    default:
+        break;
+    }
+
+    msix_write_completion(curr);
+    vcpu_end_shutdown_deferral(curr);
+}
+
 static bool_t hvm_wait_for_io(struct hvm_ioreq_vcpu *sv, ioreq_t *p)
 {
     /* NB. Optimised for common case (p->state == STATE_IOREQ_NONE). */
@@ -2664,37 +2700,6 @@ int hvm_send_assist_req(struct hvm_ioreq_server *s, ioreq_t *proto_p)
     return X86EMUL_UNHANDLEABLE;
 }
 
-void hvm_complete_assist_req(ioreq_t *p)
-{
-    switch ( p->type )
-    {
-    case IOREQ_TYPE_PCI_CONFIG:
-        ASSERT_UNREACHABLE();
-        break;
-    case IOREQ_TYPE_COPY:
-    case IOREQ_TYPE_PIO:
-        if ( p->dir == IOREQ_READ )
-        {
-            if ( !p->data_is_ptr )
-                p->data = ~0ul;
-            else
-            {
-                int i, step = p->df ? -p->size : p->size;
-                uint32_t data = ~0;
-
-                for ( i = 0; i < p->count; i++ )
-                    hvm_copy_to_guest_phys(p->data + step * i, &data,
-                                           p->size);
-            }
-        }
-        /* FALLTHRU */
-    default:
-        p->state = STATE_IORESP_READY;
-        hvm_io_assist(p);
-        break;
-    }
-}
-
 void hvm_broadcast_assist_req(ioreq_t *p)
 {
     struct domain *d = current->domain;
diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c
index 2c88ddb..fe099d8 100644
--- a/xen/arch/x86/hvm/io.c
+++ b/xen/arch/x86/hvm/io.c
@@ -169,45 +169,6 @@ int handle_pio(uint16_t port, unsigned int size, int dir)
     return 1;
 }
 
-void hvm_io_assist(ioreq_t *p)
-{
-    struct vcpu *curr = current;
-    struct hvm_vcpu_io *vio = &curr->arch.hvm_vcpu.hvm_io;
-    enum hvm_io_state io_state;
-
-    p->state = STATE_IOREQ_NONE;
-
-    io_state = vio->io_state;
-    vio->io_state = HVMIO_none;
-
-    switch ( io_state )
-    {
-    case HVMIO_awaiting_completion:
-        vio->io_state = HVMIO_completed;
-        vio->io_data = p->data;
-        break;
-    case HVMIO_handle_mmio_awaiting_completion:
-        vio->io_state = HVMIO_completed;
-        vio->io_data = p->data;
-        (void)handle_mmio();
-        break;
-    case HVMIO_handle_pio_awaiting_completion:
-        if ( vio->io_size == 4 ) /* Needs zero extension. */
-            guest_cpu_user_regs()->rax = (uint32_t)p->data;
-        else
-            memcpy(&guest_cpu_user_regs()->rax, &p->data, vio->io_size);
-        break;
-    default:
-        break;
-    }
-
-    if ( p->state == STATE_IOREQ_NONE )
-    {
-        msix_write_completion(curr);
-        vcpu_end_shutdown_deferral(curr);
-    }
-}
-
 static bool_t dpci_portio_accept(const struct hvm_io_handler *handler,
                                  const ioreq_t *p)
 {
diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
index 57f9605..9792e15 100644
--- a/xen/include/asm-x86/hvm/hvm.h
+++ b/xen/include/asm-x86/hvm/hvm.h
@@ -232,7 +232,6 @@ struct hvm_ioreq_server *hvm_select_ioreq_server(struct domain *d,
                                                  ioreq_t *p);
 int hvm_send_assist_req(struct hvm_ioreq_server *s, ioreq_t *p);
 void hvm_broadcast_assist_req(ioreq_t *p);
-void hvm_complete_assist_req(ioreq_t *p);
 
 void hvm_get_guest_pat(struct vcpu *v, u64 *guest_pat);
 int hvm_set_guest_pat(struct vcpu *v, u64 guest_pat);
diff --git a/xen/include/asm-x86/hvm/io.h b/xen/include/asm-x86/hvm/io.h
index 8394959..8ab63a1 100644
--- a/xen/include/asm-x86/hvm/io.h
+++ b/xen/include/asm-x86/hvm/io.h
@@ -125,7 +125,6 @@ int handle_mmio_with_translation(unsigned long gva, unsigned long gpfn,
                                  struct npfec);
 int handle_pio(uint16_t port, unsigned int size, int dir);
 void hvm_interrupt_post(struct vcpu *v, int vector, int type);
-void hvm_io_assist(ioreq_t *p);
 void hvm_dpci_eoi(struct domain *d, unsigned int guest_irq,
                   const union vioapic_redir_entry *ent);
 void msix_write_completion(struct vcpu *);
-- 
1.7.10.4