[Xen-devel] [PATCH v3 17/18] x86/hvm: always re-emulate I/O from a buffer

[Paul Durrant <paul.durrant@xxxxxxxxxx>]

If memory mapped I/O is 'chunked' then the I/O must be re-emulated,
otherwise only the first chunk will be processed. This patch makes
sure all I/O from a buffer is re-emulated regardless of whether it
is a read or a write.

Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
Cc: Keir Fraser <keir@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/hvm/emulate.c     |    4 ++--
 xen/arch/x86/hvm/hvm.c         |   13 ++++++++-----
 xen/include/asm-x86/hvm/vcpu.h |    3 +--
 3 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 57a93f2..d953cdb 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -148,7 +148,7 @@ static int hvmemul_do_io(
              (p.data_is_ptr != data_is_addr) )
             domain_crash(curr->domain);
 
-        if ( data_is_addr || dir == IOREQ_WRITE )
+        if ( data_is_addr )
             return X86EMUL_UNHANDLEABLE;
         goto finish_access;
     default:
@@ -188,7 +188,7 @@ static int hvmemul_do_io(
             rc = hvm_send_assist_req(s, &p);
             if ( rc != X86EMUL_RETRY )
                 vio->io_req.state = STATE_IOREQ_NONE;
-            else if ( data_is_addr || dir == IOREQ_WRITE )
+            else if ( data_is_addr )
                 rc = X86EMUL_OKAY;
         }
         break;
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 8abf29b..c062c9f 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -501,11 +501,14 @@ void hvm_do_resume(struct vcpu *v)
         (void)handle_mmio();
         break;
     case HVMIO_pio_completion:
-        if ( vio->io_req.size == 4 ) /* Needs zero extension. */
-            guest_cpu_user_regs()->rax = (uint32_t)vio->io_req.data;
-        else
-            memcpy(&guest_cpu_user_regs()->rax, &vio->io_req.data,
-                   vio->io_req.size);
+        if ( vio->io_req.dir == IOREQ_READ )
+        {
+            if ( vio->io_req.size == 4 ) /* Needs zero extension. */
+                guest_cpu_user_regs()->rax = (uint32_t)vio->io_req.data;
+            else
+                memcpy(&guest_cpu_user_regs()->rax, &vio->io_req.data,
+                       vio->io_req.size);
+        }
         vio->io_req.state = STATE_IOREQ_NONE;
         break;
     case HVMIO_realmode_completion:
diff --git a/xen/include/asm-x86/hvm/vcpu.h b/xen/include/asm-x86/hvm/vcpu.h
index 7338638..008c8fa 100644
--- a/xen/include/asm-x86/hvm/vcpu.h
+++ b/xen/include/asm-x86/hvm/vcpu.h
@@ -49,8 +49,7 @@ struct hvm_vcpu_io {
 
 #define HVMIO_NEED_COMPLETION(_vio) \
     ( ((_vio)->io_req.state == STATE_IOREQ_READY) &&    \
-      !(_vio)->io_req.data_is_ptr && \
-      ((_vio)->io_req.dir == IOREQ_READ) )
+      !(_vio)->io_req.data_is_ptr )
 
     /*
      * HVM emulation:
-- 
1.7.10.4


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