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Re: [Xen-devel] [PATCH v2 17/29] Ovmf/Xen: refactor XenBusDxe hypercall implementation



On Mon, 26 Jan 2015, Ard Biesheuvel wrote:
> 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
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> ---
>  OvmfPkg/XenBusDxe/EventChannel.c      | 11 +++--------
>  OvmfPkg/XenBusDxe/GrantTable.c        |  4 ++--
>  OvmfPkg/XenBusDxe/Ia32/hypercall.nasm |  6 +++---
>  OvmfPkg/XenBusDxe/X64/hypercall.nasm  |  6 +++---
>  OvmfPkg/XenBusDxe/XenBusDxe.c         | 44 
> +++++++++++++++++++++++++++++++++++++++++++-
>  OvmfPkg/XenBusDxe/XenBusDxe.h         |  1 -
>  OvmfPkg/XenBusDxe/XenHypercall.c      | 50 
> ++++++++++++++------------------------------------
>  OvmfPkg/XenBusDxe/XenHypercall.h      | 28 +++-------------------------
>  OvmfPkg/XenBusDxe/XenStore.c          |  4 ++--
>  9 files changed, 73 insertions(+), 81 deletions(-)
> 
> diff --git a/OvmfPkg/XenBusDxe/EventChannel.c 
> b/OvmfPkg/XenBusDxe/EventChannel.c
> index 03efaf9cb904..a86323e6adfd 100644
> --- a/OvmfPkg/XenBusDxe/EventChannel.c
> +++ b/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);
>  }
> diff --git a/OvmfPkg/XenBusDxe/GrantTable.c b/OvmfPkg/XenBusDxe/GrantTable.c
> index 8405edc51bc4..53cb99f0e004 100644
> --- a/OvmfPkg/XenBusDxe/GrantTable.c
> +++ b/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));
>      }
> diff --git a/OvmfPkg/XenBusDxe/Ia32/hypercall.nasm 
> b/OvmfPkg/XenBusDxe/Ia32/hypercall.nasm
> index 8547c30b81ee..e0fa71bb5ba8 100644
> --- a/OvmfPkg/XenBusDxe/Ia32/hypercall.nasm
> +++ b/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)
> -ASM_PFX(XenHypercall2):
> +global 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
> diff --git a/OvmfPkg/XenBusDxe/X64/hypercall.nasm 
> b/OvmfPkg/XenBusDxe/X64/hypercall.nasm
> index 177f271ef094..5e6a0c05c5c4 100644
> --- a/OvmfPkg/XenBusDxe/X64/hypercall.nasm
> +++ b/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)
> -ASM_PFX(XenHypercall2):
> +global ASM_PFX(__XenHypercall2)
> +ASM_PFX(__XenHypercall2):
>    push rdi
>    push rsi
>    ; Copy HypercallAddr to rax
> diff --git a/OvmfPkg/XenBusDxe/XenBusDxe.c b/OvmfPkg/XenBusDxe/XenBusDxe.c
> index 7a7fd82d559d..d333b331b6db 100644
> --- a/OvmfPkg/XenBusDxe/XenBusDxe.c
> +++ b/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
> @@ -52,6 +54,46 @@ 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.
>  
>    @param  ImageHandle           Handle that identifies the image to be 
> unloaded.
> @@ -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;
> diff --git a/OvmfPkg/XenBusDxe/XenBusDxe.h b/OvmfPkg/XenBusDxe/XenBusDxe.h
> index 80253b7d1ca9..9b7219906a69 100644
> --- a/OvmfPkg/XenBusDxe/XenBusDxe.h
> +++ b/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;
>  };
>  
> diff --git a/OvmfPkg/XenBusDxe/XenHypercall.c 
> b/OvmfPkg/XenBusDxe/XenHypercall.c
> index 34d92e76b7e3..9bcf3197633e 100644
> --- a/OvmfPkg/XenBusDxe/XenHypercall.c
> +++ b/OvmfPkg/XenBusDxe/XenHypercall.c
> @@ -23,9 +23,10 @@
>  #include <IndustryStandard/Xen/hvm/params.h>
>  #include <IndustryStandard/Xen/memory.h>
>  
> +STATIC VOID       *Hyperpage;
> +
>  EFI_STATUS
>  XenHyperpageInit (
> -  IN OUT XENBUS_DEVICE *Dev
>    )
>  {
>    EFI_HOB_GUID_TYPE   *GuidHob;
> @@ -36,24 +37,21 @@ 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 +64,33 @@ XenHypercallHvmGetParam (
>  
>  INTN
>  XenHypercallMemoryOp (
> -  IN     XENBUS_DEVICE *Dev,
>    IN     UINTN Operation,
>    IN OUT VOID *Arguments
>    )
>  {
> -  ASSERT (Dev->Hyperpage != NULL);
> -  return XenHypercall2 ((UINT8*)Dev->Hyperpage + __HYPERVISOR_memory_op * 32,
> +  return XenHypercall2 (__HYPERVISOR_memory_op,
>                          Operation, (INTN) Arguments);
>  }
>  
>  INTN
>  XenHypercallEventChannelOp (
> -  IN     XENBUS_DEVICE *Dev,
>    IN     INTN Operation,
>    IN OUT VOID *Arguments
>    )
>  {
> -  ASSERT (Dev->Hyperpage != NULL);
> -  return XenHypercall2 ((UINT8*)Dev->Hyperpage + 
> __HYPERVISOR_event_channel_op * 32,
> +  return XenHypercall2 (__HYPERVISOR_event_channel_op,
>                          Operation, (INTN) Arguments);
>  }
>  
> -EFI_STATUS
> -XenGetSharedInfoPage (
> -  IN OUT XENBUS_DEVICE *Dev
> +INTN
> +EFIAPI
> +XenHypercall2 (
> +  IN     INTN HypercallID,
> +  IN OUT INTN Arg1,
> +  IN OUT INTN Arg2
>    )
>  {
> -  xen_add_to_physmap_t Parameter;
> -
> -  ASSERT (Dev->SharedInfo == NULL);
> +  ASSERT (HyperPage != 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 (Dev, XENMEM_add_to_physmap, &Parameter) != 0) {
> -    FreePages (Dev->SharedInfo, 1);
> -    Dev->SharedInfo = NULL;
> -    return EFI_LOAD_ERROR;
> -  }
> -
> -  return EFI_SUCCESS;
> +  return __XenHypercall2 ((UINT8*)HyperPage + HypercallID * 32, Arg1, Arg2);
                                        ^ shouldn't it be Hyperpage?

>  }
> diff --git a/OvmfPkg/XenBusDxe/XenHypercall.h 
> b/OvmfPkg/XenBusDxe/XenHypercall.h
> index 06693830e16e..9d49e33eb5af 100644
> --- a/OvmfPkg/XenBusDxe/XenHypercall.h
> +++ b/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
> diff --git a/OvmfPkg/XenBusDxe/XenStore.c b/OvmfPkg/XenBusDxe/XenStore.c
> index 2df8f5348585..7ec1e634bc5c 100644
> --- a/OvmfPkg/XenBusDxe/XenStore.c
> +++ b/OvmfPkg/XenBusDxe/XenStore.c
> @@ -1057,8 +1057,8 @@ XenStoreInit (
>  
>    xs.Dev = Dev;
>  
> -  xs.EventChannel = (evtchn_port_t)XenHypercallHvmGetParam (Dev, 
> HVM_PARAM_STORE_EVTCHN);
> -  XenStoreGpfn = (UINTN)XenHypercallHvmGetParam (Dev, HVM_PARAM_STORE_PFN);
> +  xs.EventChannel = (evtchn_port_t)XenHypercallHvmGetParam 
> (HVM_PARAM_STORE_EVTCHN);
> +  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));
> -- 
> 1.8.3.2
> 

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