Re: [Xen-devel] [PATCH v1 12/21] Ovmf/Xen: fix pointer to int cast in XenBusDxe

[Laszlo Ersek <lersek@xxxxxxxxxx>]

On 01/23/15 16:03, Ard Biesheuvel wrote:
> On ARM, xen_pfn_t is 64 bits but the size of a pointer is only
> 32 bits, so casting between them needs to go via (UINTN)
> 
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> ---
>  OvmfPkg/XenBusDxe/GrantTable.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/OvmfPkg/XenBusDxe/GrantTable.c b/OvmfPkg/XenBusDxe/GrantTable.c
> index 37d3bf786c64..cc6f045c9827 100644
> --- a/OvmfPkg/XenBusDxe/GrantTable.c
> +++ b/OvmfPkg/XenBusDxe/GrantTable.c
> @@ -160,7 +160,7 @@ XenGrantTableInit (
>      Parameters.domid = DOMID_SELF;
>      Parameters.idx = Index;
>      Parameters.space = XENMAPSPACE_grant_table;
> -    Parameters.gpfn = (((xen_pfn_t) GrantTable) >> EFI_PAGE_SHIFT) + Index;
> +    Parameters.gpfn = (((xen_pfn_t)(UINTN) GrantTable) >> EFI_PAGE_SHIFT) + 
> Index;
>      ReturnCode = XenHypercallMemoryOp (Dev, XENMEM_add_to_physmap, 
> &Parameters);
>      if (ReturnCode != 0) {
>        DEBUG ((EFI_D_ERROR, "Xen GrantTable, add_to_physmap hypercall error: 
> %d\n", ReturnCode));
> @@ -182,7 +182,7 @@ XenGrantTableDeinit (
>  
>    for (Index = NR_GRANT_FRAMES - 1; Index >= 0; Index--) {
>      Parameters.domid = DOMID_SELF;
> -    Parameters.gpfn = (((xen_pfn_t) GrantTable) >> EFI_PAGE_SHIFT) + Index;
> +    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);
>      if (ReturnCode != 0) {
> 

On a 32-bit platform you shouldn't bit-shift 64-bit integers, because
the compiler might generate calls to intrinsic functions, and those are
not allowed in edk2.

Please use RShiftU64() in addition to the above changes.

(Example: "MdePkg/Library/BaseLib/Ia32/RShiftU64.S".)

Thanks,
Laszlo

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