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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH-4.16 v2] xen/efi: Fix Grub2 boot on arm64
On Thu, 4 Nov 2021, Jan Beulich wrote:
> On 04.11.2021 15:12, Luca Fancellu wrote:
> > --- a/xen/common/efi/boot.c
> > +++ b/xen/common/efi/boot.c
> > @@ -449,6 +449,15 @@ static EFI_FILE_HANDLE __init
> > get_parent_handle(EFI_LOADED_IMAGE *loaded_image,
> > CHAR16 *pathend, *ptr;
> > EFI_STATUS ret;
> >
> > + /*
> > + * Grub2 running on top of EDK2 has been observed to supply a NULL
> > + * DeviceHandle. We can't use that to gain access to the filesystem.
> > + * However the system can still boot if it doesn’t require access to
> > the
> > + * filesystem.
> > + */
> > + if ( !loaded_image->DeviceHandle )
> > + return NULL;
> > +
> > do {
> > EFI_FILE_IO_INTERFACE *fio;
> >
> > @@ -581,6 +590,8 @@ static bool __init read_file(EFI_FILE_HANDLE
> > dir_handle, CHAR16 *name,
> > EFI_STATUS ret;
> > const CHAR16 *what = NULL;
> >
> > + if ( !dir_handle )
> > + blexit(L"Error: No access to the filesystem");
> > if ( !name )
> > PrintErrMesg(L"No filename", EFI_OUT_OF_RESOURCES);
> > ret = dir_handle->Open(dir_handle, &FileHandle, name,
> > @@ -1333,8 +1344,18 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE
> > *SystemTable)
> > EFI_FILE_HANDLE handle = get_parent_handle(loaded_image,
> > &file_name);
> >
> > - handle->Close(handle);
> > - *argv = file_name;
> > + if ( !handle )
> > + {
> > + PrintErr(L"Error retrieving image name: no filesystem
> > access."
> > + L" Setting default to xen.efi");
> > + PrintErr(newline);
> > + *argv = L"xen.efi";
> > + }
> > + else
> > + {
> > + handle->Close(handle);
> > + *argv = file_name;
> > + }
> > }
> >
> > name.s = get_value(&cfg, section.s, "options");
> > @@ -1369,7 +1390,8 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE
> > *SystemTable)
> > /* Get the number of boot modules specified on the DT or an error (<0)
> > */
> > dt_modules_found = efi_check_dt_boot(dir_handle);
> >
> > - dir_handle->Close(dir_handle);
> > + if ( dir_handle )
> > + dir_handle->Close(dir_handle);
> >
> > if ( dt_modules_found < 0 )
> > /* efi_check_dt_boot throws some error */
> >
>
> I'm sorry, but I think we need to take a step back here and revisit
> the earlier change. If that hadn't moved obtaining dir_handle out by
> one level of scope, nothing bad would have happened to the case that
> you're now trying to fix, I understand? So perhaps that part wants
> undoing, with efi_check_dt_boot() instead getting passed loaded_image.
> That way, down the call tree the needed handle can be obtained via
> another call to get_parent_handle(), and quite likely in the scenario
> you're trying to fix here execution wouldn't even make it there. This
> then wouldn't be much different to the image name retrieval calling
> get_parent_handle() a 2nd time, rather than trying to re-use
> dir_handle.
>
> Net effect being that I think get_parent_handle() would then again
> only be called when the returned handle is actually needed, and hence
> when failure of HandleProtocol() (for DeviceHandle being NULL just
> like for any other reason) is indeed an error that needs reporting.
In my opinion the current version is good enough. Regardless, I looked
at your suggestion into details. As it took me some time to understand
it, I thought I would share the code changes that I think correspond to
what you wrote. Does everything check out?
If so, I think it looks fine, maybe a bit better than the current
version. I'll leave that to you and Luca.
diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
index c3ae9751ab..9dcd8547cd 100644
--- a/xen/arch/arm/efi/efi-boot.h
+++ b/xen/arch/arm/efi/efi-boot.h
@@ -8,6 +8,8 @@
#include <asm/setup.h>
#include <asm/smp.h>
+extern EFI_FILE_HANDLE __init get_parent_handle(EFI_LOADED_IMAGE *loaded_image,
+ CHAR16 **leaf);
typedef struct {
char *name;
unsigned int name_len;
@@ -54,7 +56,7 @@ static int handle_module_node(EFI_FILE_HANDLE dir_handle,
bool is_domu_module);
static int handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
int domain_node);
-static int efi_check_dt_boot(EFI_FILE_HANDLE dir_handle);
+static int efi_check_dt_boot(EFI_LOADED_IMAGE *loaded_image);
#define DEVICE_TREE_GUID \
{0xb1b621d5, 0xf19c, 0x41a5, {0x83, 0x0b, 0xd9, 0x15, 0x2c, 0x69, 0xaa, 0xe0}}
@@ -851,10 +853,14 @@ static int __init
handle_dom0less_domain_node(EFI_FILE_HANDLE dir_handle,
* dom0 and domU guests to be loaded.
* Returns the number of multiboot modules found or a negative number for
error.
*/
-static int __init efi_check_dt_boot(EFI_FILE_HANDLE dir_handle)
+static int __init efi_check_dt_boot(EFI_LOADED_IMAGE *loaded_image)
{
int chosen, node, addr_len, size_len;
unsigned int i = 0, modules_found = 0;
+ EFI_FILE_HANDLE dir_handle;
+ CHAR16 *file_name;
+
+ dir_handle = get_parent_handle(loaded_image, &file_name);
/* Check for the chosen node in the current DTB */
chosen = setup_chosen_node(fdt, &addr_len, &size_len);
@@ -895,6 +901,8 @@ static int __init efi_check_dt_boot(EFI_FILE_HANDLE
dir_handle)
efi_bs->FreePool(modules[i].name);
}
+ dir_handle->Close(dir_handle);
+
return modules_found;
}
diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index 112b7e7571..2407671a7d 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -167,7 +167,7 @@ static void __init PrintErr(const CHAR16 *s)
}
#ifndef CONFIG_HAS_DEVICE_TREE
-static int __init efi_check_dt_boot(EFI_FILE_HANDLE dir_handle)
+static int __init efi_check_dt_boot(EFI_LOADED_IMAGE *loaded_image)
{
return 0;
}
@@ -439,8 +439,8 @@ static unsigned int __init get_argv(unsigned int argc,
CHAR16 **argv,
return argc;
}
-static EFI_FILE_HANDLE __init get_parent_handle(EFI_LOADED_IMAGE *loaded_image,
- CHAR16 **leaf)
+EFI_FILE_HANDLE __init get_parent_handle(EFI_LOADED_IMAGE *loaded_image,
+ CHAR16 **leaf)
{
static EFI_GUID __initdata fs_protocol = SIMPLE_FILE_SYSTEM_PROTOCOL;
static CHAR16 __initdata buffer[512];
@@ -1236,9 +1236,6 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE
*SystemTable)
efi_arch_relocate_image(0);
- /* Get the file system interface. */
- dir_handle = get_parent_handle(loaded_image, &file_name);
-
if ( use_cfg_file )
{
UINTN depth, cols, rows, size;
@@ -1251,6 +1248,9 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE
*SystemTable)
gop = efi_get_gop();
+ /* Get the file system interface. */
+ dir_handle = get_parent_handle(loaded_image, &file_name);
+
/* Read and parse the config file. */
if ( read_section(loaded_image, L"config", &cfg, NULL) )
PrintStr(L"Using builtin config file\r\n");
@@ -1344,18 +1344,8 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE
*SystemTable)
EFI_FILE_HANDLE handle = get_parent_handle(loaded_image,
&file_name);
- if ( !handle )
- {
- PrintErr(L"Error retrieving image name: no filesystem access."
- L" Setting default to xen.efi");
- PrintErr(newline);
- *argv = L"xen.efi";
- }
- else
- {
- handle->Close(handle);
- *argv = file_name;
- }
+ handle->Close(handle);
+ *argv = file_name;
}
name.s = get_value(&cfg, section.s, "options");
@@ -1383,15 +1373,14 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE
*SystemTable)
efi_bs->FreePages(cfg.addr, PFN_UP(cfg.size));
cfg.addr = 0;
+ dir_handle->Close(dir_handle);
+
if ( gop && !base_video )
gop_mode = efi_find_gop_mode(gop, cols, rows, depth);
}
/* Get the number of boot modules specified on the DT or an error (<0) */
- dt_modules_found = efi_check_dt_boot(dir_handle);
-
- if ( dir_handle )
- dir_handle->Close(dir_handle);
+ dt_modules_found = efi_check_dt_boot(loaded_image);
if ( dt_modules_found < 0 )
/* efi_check_dt_boot throws some error */
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