[Xen-devel] [XEN][RFC PATCH 06/15] hvm-io: IO refactoring with ioreq server

[Julien Grall <julien.grall@xxxxxxxxxx>]

This modify several parts of the IO handle.
Each vcpu now contains a pointer to the current IO shared page.
A default shared page has been created for IO handle by Xen.
Each time that Xen receives an ioreq, it will use the default
shared page and set the right shared page when it's able to
know the server.

Moreover, all IO which are unhandleabled by Xen or by a server
will be directly discard by Xen.

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
---
 xen/arch/x86/hvm/emulate.c        |   56 +++++++++++++++++++++++++++++++++++++
 xen/arch/x86/hvm/hvm.c            |    5 ++-
 xen/include/asm-x86/hvm/support.h |   26 ++++++++++++++--
 3 files changed, 81 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 82efd1a..284c8b2 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -49,6 +49,55 @@ static void hvmtrace_io_assist(int is_mmio, ioreq_t *p)
     trace_var(event, 0/*!cycles*/, size, buffer);
 }
 
+static int hvmemul_prepare_assist(ioreq_t *p)
+{
+    struct vcpu *v = current;
+    struct hvm_ioreq_server *s;
+    int i;
+    int sign;
+    uint32_t data = ~0;
+
+    if ( p->type == IOREQ_TYPE_PCI_CONFIG )
+        return X86EMUL_UNHANDLEABLE;
+
+    spin_lock(&v->domain->arch.hvm_domain.ioreq_server_lock);
+    for ( s = v->domain->arch.hvm_domain.ioreq_server_list; s; s = s->next )
+    {
+        struct hvm_io_range *x = (p->type == IOREQ_TYPE_COPY)
+            ? s->mmio_range_list : s->portio_range_list;
+
+        for ( ; x; x = x->next )
+        {
+            if ( (p->addr >= x->s) && (p->addr <= x->e) )
+                goto done_server_scan;
+        }
+    }
+
+    spin_unlock(&v->domain->arch.hvm_domain.ioreq_server_lock);
+
+    sign = p->df ? -1 : 1;
+
+    if ( p->dir != IOREQ_WRITE )
+    {
+        if ( !p->data_is_ptr )
+            p->data = ~0;
+        else
+        {
+            for ( i = 0; i < p->count; i++ )
+                hvm_copy_to_guest_phys(p->data + sign * i * p->size, &data,
+                                       p->size);
+        }
+    }
+
+    return X86EMUL_OKAY;
+
+  done_server_scan:
+    set_ioreq(v, &s->ioreq, p);
+    spin_unlock(&v->domain->arch.hvm_domain.ioreq_server_lock);
+
+    return X86EMUL_UNHANDLEABLE;
+}
+
 static int hvmemul_do_io(
     int is_mmio, paddr_t addr, unsigned long *reps, int size,
     paddr_t ram_gpa, int dir, int df, void *p_data)
@@ -182,6 +231,10 @@ static int hvmemul_do_io(
         (p_data == NULL) ? HVMIO_dispatched : HVMIO_awaiting_completion;
     vio->io_size = size;
 
+    /* Use the default shared page */
+    current->arch.hvm_vcpu.ioreq = &curr->domain->arch.hvm_domain.ioreq;
+    p = get_ioreq(current);
+
     p->dir = dir;
     p->data_is_ptr = value_is_ptr;
     p->type = is_mmio ? IOREQ_TYPE_COPY : IOREQ_TYPE_PIO;
@@ -204,6 +257,9 @@ static int hvmemul_do_io(
         rc = hvm_portio_intercept(p);
     }
 
+    if ( rc == X86EMUL_UNHANDLEABLE )
+        rc = hvmemul_prepare_assist(p);
+
     switch ( rc )
     {
     case X86EMUL_OKAY:
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 3117ae1..e8ea42e 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -1204,14 +1204,15 @@ bool_t hvm_send_assist_req(struct vcpu *v)
         return 0;
     }
 
-    prepare_wait_on_xen_event_channel(v->arch.hvm_vcpu.xen_port);
+    prepare_wait_on_xen_event_channel(p->vp_eport);
 
     /*
      * Following happens /after/ blocking and setting up ioreq contents.
      * prepare_wait_on_xen_event_channel() is an implicit barrier.
      */
     p->state = STATE_IOREQ_READY;
-    notify_via_xen_event_channel(v->domain, v->arch.hvm_vcpu.xen_port);
+
+    notify_via_xen_event_channel(v->domain, p->vp_eport);
 
     return 1;
 }
diff --git a/xen/include/asm-x86/hvm/support.h 
b/xen/include/asm-x86/hvm/support.h
index f9b102f..44acd37 100644
--- a/xen/include/asm-x86/hvm/support.h
+++ b/xen/include/asm-x86/hvm/support.h
@@ -29,13 +29,31 @@
 
 static inline ioreq_t *get_ioreq(struct vcpu *v)
 {
-    struct domain *d = v->domain;
-    shared_iopage_t *p = d->arch.hvm_domain.ioreq.va;
-    ASSERT((v == current) || spin_is_locked(&d->arch.hvm_domain.ioreq.lock));
-    ASSERT(d->arch.hvm_domain.ioreq.va != NULL);
+    shared_iopage_t *p = v->arch.hvm_vcpu.ioreq->va;
+    ASSERT((v == current) || spin_is_locked(&v->arch.hvm_vcpu.ioreq->lock));
+    ASSERT(v->arch.hvm_vcpu.ioreq->va != NULL);
     return &p->vcpu_ioreq[v->vcpu_id];
 }
 
+static inline void set_ioreq(struct vcpu *v, struct hvm_ioreq_page *page,
+                            ioreq_t *p)
+{
+    ioreq_t *np;
+
+    v->arch.hvm_vcpu.ioreq = page;
+    spin_lock(&v->arch.hvm_vcpu.ioreq->lock);
+    np = get_ioreq(v);
+    np->dir = p->dir;
+    np->data_is_ptr = p->data_is_ptr;
+    np->type = p->type;
+    np->size = p->size;
+    np->addr = p->addr;
+    np->count = p->count;
+    np->df = p->df;
+    np->data = p->data;
+    spin_unlock(&v->arch.hvm_vcpu.ioreq->lock);
+}
+
 #define HVM_DELIVER_NO_ERROR_CODE  -1
 
 #ifndef NDEBUG
-- 
Julien Grall


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