Ovmf/Xen: refactor XenBusDxe hypercall implementation

This refactors the Xen hypercall implementation that is part of the
XenBusDxe driver, in preparation of splitting it off entirely into
a XenHypercallLib library. This involves:
- removing the dependency on XENBUS_DEVICE* pointers in the XenHypercall()
  prototypes
- moving the discovered hyperpage address to a global variable
- moving XenGetSharedInfoPage() to its only user XenBusDxe.c (the shared info
  page is not strictly part of the Xen hypercall interface, and is not used
  by other expected users of XenHypercallLib such as the Xen console version
  of SerialPortLib
- reimplement XenHypercall2() in C and move the indexing of the hyperpage
  there; the existing asm implementations are renamed to __XenHypercall2() and
  invoked from the new C implementation.

Contributed-under: TianoCore Contribution Agreement 1.0
Acked-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16969 6f19259b-4bc3-4df7-8a09-765794883524

OvmfPkg/XenBusDxe/EventChannel.c

@@ -28,7 +28,7 @@ XenEventChannelNotify (
   evtchn_send_t Send;
 
   Send.port = Port;
-  ReturnCode = XenHypercallEventChannelOp (Dev, EVTCHNOP_send, &Send);
+  ReturnCode = XenHypercallEventChannelOp (EVTCHNOP_send, &Send);
   return (UINT32)ReturnCode;
 }
 
@@ -40,15 +40,12 @@ XenBusEventChannelAllocate (
   OUT evtchn_port_t   *Port
   )
 {
-  XENBUS_PRIVATE_DATA *Private;
   evtchn_alloc_unbound_t Parameter;
   UINT32 ReturnCode;
 
-  Private = XENBUS_PRIVATE_DATA_FROM_THIS (This);
-
   Parameter.dom = DOMID_SELF;
   Parameter.remote_dom = DomainId;
-  ReturnCode = (UINT32)XenHypercallEventChannelOp (Private->Dev,
+  ReturnCode = (UINT32)XenHypercallEventChannelOp (
                                    EVTCHNOP_alloc_unbound,
                                    &Parameter);
   if (ReturnCode != 0) {
@@ -79,10 +76,8 @@ XenBusEventChannelClose (
   IN evtchn_port_t   Port
   )
 {
-  XENBUS_PRIVATE_DATA *Private;
   evtchn_close_t Close;
 
-  Private = XENBUS_PRIVATE_DATA_FROM_THIS (This);
   Close.port = Port;
-  return (UINT32)XenHypercallEventChannelOp (Private->Dev, EVTCHNOP_close, &Close);
+  return (UINT32)XenHypercallEventChannelOp (EVTCHNOP_close, &Close);
 }

OvmfPkg/XenBusDxe/GrantTable.c

@@ -161,7 +161,7 @@ XenGrantTableInit (
     Parameters.idx = Index;
     Parameters.space = XENMAPSPACE_grant_table;
     Parameters.gpfn = (xen_pfn_t) ((UINTN) GrantTable >> EFI_PAGE_SHIFT) + Index;
-    ReturnCode = XenHypercallMemoryOp (Dev, XENMEM_add_to_physmap, &Parameters);
+    ReturnCode = XenHypercallMemoryOp (XENMEM_add_to_physmap, &Parameters);
     if (ReturnCode != 0) {
       DEBUG ((EFI_D_ERROR, "Xen GrantTable, add_to_physmap hypercall error: %d\n", ReturnCode));
     }
@@ -184,7 +184,7 @@ XenGrantTableDeinit (
     Parameters.domid = DOMID_SELF;
     Parameters.gpfn = (xen_pfn_t) ((UINTN) GrantTable >> EFI_PAGE_SHIFT) + Index;
     DEBUG ((EFI_D_INFO, "Xen GrantTable, removing %X\n", Parameters.gpfn));
-    ReturnCode = XenHypercallMemoryOp (Dev, XENMEM_remove_from_physmap, &Parameters);
+    ReturnCode = XenHypercallMemoryOp (XENMEM_remove_from_physmap, &Parameters);
     if (ReturnCode != 0) {
       DEBUG ((EFI_D_ERROR, "Xen GrantTable, remove_from_physmap hypercall error: %d\n", ReturnCode));
     }

OvmfPkg/XenBusDxe/Ia32/hypercall.nasm

@@ -2,13 +2,13 @@ SECTION .text
 
 ; INTN
 ; EFIAPI
-; XenHypercall2 (
+; __XenHypercall2 (
 ;   IN     VOID *HypercallAddr,
 ;   IN OUT INTN Arg1,
 ;   IN OUT INTN Arg2
 ;   );
-global ASM_PFX(XenHypercall2)
+global ASM_PFX(__XenHypercall2)
-ASM_PFX(XenHypercall2):
+ASM_PFX(__XenHypercall2):
   ; Save only ebx, ecx is supposed to be a scratch register and needs to be
   ; saved by the caller
   push ebx

OvmfPkg/XenBusDxe/X64/hypercall.nasm

@@ -3,13 +3,13 @@ SECTION .text
 
 ; INTN
 ; EFIAPI
-; XenHypercall2 (
+; __XenHypercall2 (
 ;   IN     VOID *HypercallAddr,
 ;   IN OUT INTN Arg1,
 ;   IN OUT INTN Arg2
 ;   );
-global ASM_PFX(XenHypercall2)
+global ASM_PFX(__XenHypercall2)
-ASM_PFX(XenHypercall2):
+ASM_PFX(__XenHypercall2):
   push rdi
   push rsi
   ; Copy HypercallAddr to rax

OvmfPkg/XenBusDxe/XenBusDxe.c

@@ -34,6 +34,8 @@
 #include "XenStore.h"
 #include "XenBus.h"
 
+#include <IndustryStandard/Xen/hvm/params.h>
+#include <IndustryStandard/Xen/memory.h>
 
 ///
 /// Driver Binding Protocol instance
@@ -51,6 +53,46 @@ EFI_DRIVER_BINDING_PROTOCOL gXenBusDxeDriverBinding = {
 STATIC EFI_LOCK       mMyDeviceLock = EFI_INITIALIZE_LOCK_VARIABLE (TPL_CALLBACK);
 STATIC XENBUS_DEVICE *mMyDevice = NULL;
 
+/**
+  Map the shared_info_t page into memory.
+
+  @param Dev    A XENBUS_DEVICE instance.
+
+  @retval EFI_SUCCESS     Dev->SharedInfo whill contain a pointer to
+                          the shared info page
+  @retval EFI_LOAD_ERROR  The shared info page could not be mapped. The
+                          hypercall returned an error.
+**/
+STATIC
+EFI_STATUS
+XenGetSharedInfoPage (
+  IN OUT XENBUS_DEVICE *Dev
+  )
+{
+  xen_add_to_physmap_t Parameter;
+
+  ASSERT (Dev->SharedInfo == NULL);
+
+  Parameter.domid = DOMID_SELF;
+  Parameter.space = XENMAPSPACE_shared_info;
+  Parameter.idx = 0;
+
+  //
+  // using reserved page because the page is not released when Linux is
+  // starting because of the add_to_physmap. QEMU might try to access the
+  // page, and fail because it have no right to do so (segv).
+  //
+  Dev->SharedInfo = AllocateReservedPages (1);
+  Parameter.gpfn = (UINTN) Dev->SharedInfo >> EFI_PAGE_SHIFT;
+  if (XenHypercallMemoryOp (XENMEM_add_to_physmap, &Parameter) != 0) {
+    FreePages (Dev->SharedInfo, 1);
+    Dev->SharedInfo = NULL;
+    return EFI_LOAD_ERROR;
+  }
+
+  return EFI_SUCCESS;
+}
+
 /**
   Unloads an image.
 
@@ -348,7 +390,7 @@ XenBusDxeDriverBindingStart (
   MmioAddr = BarDesc->AddrRangeMin;
   FreePool (BarDesc);
 
-  Status = XenHyperpageInit (Dev);
+  Status = XenHyperpageInit ();
   if (EFI_ERROR (Status)) {
     DEBUG ((EFI_D_ERROR, "XenBus: Unable to retrieve the hyperpage.\n"));
     Status = EFI_UNSUPPORTED;

OvmfPkg/XenBusDxe/XenBusDxe.h

@@ -91,7 +91,6 @@ struct _XENBUS_DEVICE {
   EFI_DEVICE_PATH_PROTOCOL      *DevicePath;
   LIST_ENTRY                    ChildList;
 
-  VOID                          *Hyperpage;
   shared_info_t                 *SharedInfo;
 };
 

OvmfPkg/XenBusDxe/XenHypercall.c

@@ -23,9 +23,21 @@
 #include <IndustryStandard/Xen/hvm/params.h>
 #include <IndustryStandard/Xen/memory.h>
 
+STATIC VOID       *HyperPage;
+
+//
+// Interface exposed by the ASM implementation of the core hypercall
+//
+INTN
+EFIAPI
+__XenHypercall2 (
+  IN     VOID *HypercallAddr,
+  IN OUT INTN Arg1,
+  IN OUT INTN Arg2
+  );
+
 EFI_STATUS
 XenHyperpageInit (
-  IN OUT XENBUS_DEVICE *Dev
   )
 {
   EFI_HOB_GUID_TYPE   *GuidHob;
@@ -36,24 +48,21 @@ XenHyperpageInit (
     return EFI_NOT_FOUND;
   }
   XenInfo = (EFI_XEN_INFO *) GET_GUID_HOB_DATA (GuidHob);
-  Dev->Hyperpage = XenInfo->HyperPages;
+  HyperPage = XenInfo->HyperPages;
   return EFI_SUCCESS;
 }
 
 UINT64
 XenHypercallHvmGetParam (
-  IN XENBUS_DEVICE *Dev,
   IN UINT32        Index
   )
 {
   xen_hvm_param_t     Parameter;
   INTN                Error;
 
-  ASSERT (Dev->Hyperpage != NULL);
-
   Parameter.domid = DOMID_SELF;
   Parameter.index = Index;
-  Error = XenHypercall2 ((UINT8*)Dev->Hyperpage + __HYPERVISOR_hvm_op * 32,
+  Error = XenHypercall2 (__HYPERVISOR_hvm_op,
                          HVMOP_get_param, (INTN) &Parameter);
   if (Error != 0) {
     DEBUG ((EFI_D_ERROR,
@@ -66,53 +75,33 @@ XenHypercallHvmGetParam (
 
 INTN
 XenHypercallMemoryOp (
-  IN     XENBUS_DEVICE *Dev,
   IN     UINTN Operation,
   IN OUT VOID *Arguments
   )
 {
-  ASSERT (Dev->Hyperpage != NULL);
+  return XenHypercall2 (__HYPERVISOR_memory_op,
-  return XenHypercall2 ((UINT8*)Dev->Hyperpage + __HYPERVISOR_memory_op * 32,
                         Operation, (INTN) Arguments);
 }
 
 INTN
 XenHypercallEventChannelOp (
-  IN     XENBUS_DEVICE *Dev,
   IN     INTN Operation,
   IN OUT VOID *Arguments
   )
 {
-  ASSERT (Dev->Hyperpage != NULL);
+  return XenHypercall2 (__HYPERVISOR_event_channel_op,
-  return XenHypercall2 ((UINT8*)Dev->Hyperpage + __HYPERVISOR_event_channel_op * 32,
                         Operation, (INTN) Arguments);
 }
 
-EFI_STATUS
+INTN
-XenGetSharedInfoPage (
+EFIAPI
-  IN OUT XENBUS_DEVICE *Dev
+XenHypercall2 (
+  IN     UINTN  HypercallID,
+  IN OUT INTN   Arg1,
+  IN OUT INTN   Arg2
   )
 {
-  xen_add_to_physmap_t Parameter;
+  ASSERT (HyperPage != NULL);
 
-  ASSERT (Dev->SharedInfo == NULL);
+  return __XenHypercall2 ((UINT8*)HyperPage + HypercallID * 32, Arg1, Arg2);
-
-  Parameter.domid = DOMID_SELF;
-  Parameter.space = XENMAPSPACE_shared_info;
-  Parameter.idx = 0;
-
-  //
-  // using reserved page because the page is not released when Linux is
-  // starting because of the add_to_physmap. QEMU might try to access the
-  // page, and fail because it have no right to do so (segv).
-  //
-  Dev->SharedInfo = AllocateReservedPages (1);
-  Parameter.gpfn = (UINTN) Dev->SharedInfo >> EFI_PAGE_SHIFT;
-  if (XenHypercallMemoryOp (Dev, XENMEM_add_to_physmap, &Parameter) != 0) {
-    FreePages (Dev->SharedInfo, 1);
-    Dev->SharedInfo = NULL;
-    return EFI_LOAD_ERROR;
-  }
-
-  return EFI_SUCCESS;
 }

OvmfPkg/XenBusDxe/XenHypercall.h

@@ -18,9 +18,9 @@
 
 /**
   This function will put the two arguments in the right place (registers) and
-  call HypercallAddr, which correspond to an entry in the hypercall pages.
+  invoke the hypercall identified by HypercallID.
 
-  @param HypercallAddr  A memory address where the hypercall to call is.
+  @param HypercallID    The symbolic ID of the hypercall to be invoked
   @param Arg1           First argument.
   @param Arg2           Second argument.
 
@@ -29,7 +29,7 @@
 INTN
 EFIAPI
 XenHypercall2 (
-  IN     VOID *HypercallAddr,
+  IN     INTN HypercallID,
   IN OUT INTN Arg1,
   IN OUT INTN Arg2
   );
@@ -44,27 +44,23 @@ XenHypercall2 (
 **/
 EFI_STATUS
 XenHyperpageInit (
-  XENBUS_DEVICE *Dev
   );
 
 /**
   Return the value of the HVM parameter Index.
 
-  @param Dev    A XENBUS_DEVICE instance.
   @param Index  The parameter to get, e.g. HVM_PARAM_STORE_EVTCHN.
 
   @return   The value of the asked parameter or 0 in case of error.
 **/
 UINT64
 XenHypercallHvmGetParam (
-  XENBUS_DEVICE *Dev,
   UINT32 Index
   );
 
 /**
   Hypercall to do different operation on the memory.
 
-  @param Dev        A XENBUS_DEVICE instance.
   @param Operation  The operation number, e.g. XENMEM_add_to_physmap.
   @param Arguments  The arguments associated to the operation.
 
@@ -73,7 +69,6 @@ XenHypercallHvmGetParam (
 **/
 INTN
 XenHypercallMemoryOp (
-  IN     XENBUS_DEVICE *Dev,
   IN     UINTN Operation,
   IN OUT VOID *Arguments
   );
@@ -81,7 +76,6 @@ XenHypercallMemoryOp (
 /**
   Do an operation on the event channels.
 
-  @param Dev        A XENBUS_DEVICE instance.
   @param Operation  The operation number, e.g. EVTCHNOP_send.
   @param Arguments  The argument associated to the operation.
 
@@ -90,24 +84,8 @@ XenHypercallMemoryOp (
 **/
 INTN
 XenHypercallEventChannelOp (
-  IN     XENBUS_DEVICE *Dev,
   IN     INTN Operation,
   IN OUT VOID *Arguments
   );
 
-/**
-  Map the shared_info_t page into memory.
-
-  @param Dev    A XENBUS_DEVICE instance.
-
-  @retval EFI_SUCCESS     Dev->SharedInfo whill contain a pointer to
-                          the shared info page
-  @retval EFI_LOAD_ERROR  The shared info page could not be mapped. The
-                          hypercall returned an error.
-**/
-EFI_STATUS
-XenGetSharedInfoPage (
-  IN OUT XENBUS_DEVICE *Dev
-  );
-
 #endif

OvmfPkg/XenBusDxe/XenStore.c

@@ -1057,8 +1057,8 @@ XenStoreInit (
 
   xs.Dev = Dev;
 
-  xs.EventChannel = (evtchn_port_t)XenHypercallHvmGetParam (Dev, HVM_PARAM_STORE_EVTCHN);
+  xs.EventChannel = (evtchn_port_t)XenHypercallHvmGetParam (HVM_PARAM_STORE_EVTCHN);
-  XenStoreGpfn = (UINTN)XenHypercallHvmGetParam (Dev, HVM_PARAM_STORE_PFN);
+  XenStoreGpfn = (UINTN)XenHypercallHvmGetParam (HVM_PARAM_STORE_PFN);
   xs.XenStore = (VOID *) (XenStoreGpfn << EFI_PAGE_SHIFT);
   DEBUG ((EFI_D_INFO, "XenBusInit: XenBus rings @%p, event channel %x\n",
           xs.XenStore, xs.EventChannel));