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OvmfPkg: BDS: QemuBootOrder: don't leak unreferenced boot options 

The Boot#### variables that have become unreferenced in the new BootOrder
variable won't ever be automatically reused for booting. They are
"unreachable" resources that take up room in the variable store. Make an
effort to remove them.

This should plug the leak which, given sufficient reboots, exhausts the
variable store with stale Boot#### variables and renders the VM
unbootable.

Reported-by: Michael Chang <mchang@suse.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15327 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
Laszlo Ersek 2014-03-13 17:35:03 +00:00 committed by jljusten
parent de5ae37bb2
commit 1c9135a288
1 changed files with 48 additions and 6 deletions
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54
OvmfPkg/Library/PlatformBdsLib/QemuBootOrder.c
View File

@ -1120,6 +1120,47 @@ BootOrderComplete (
}
/**
Delete Boot#### variables that stand for such active boot options that have
been dropped (ie. have not been selected by either matching or "survival
policy").
@param[in] ActiveOption The array of active boot options to scan. Each
entry not marked as appended will trigger the
deletion of the matching Boot#### variable.
@param[in] ActiveCount Number of elements in ActiveOption.
**/
STATIC
VOID
PruneBootVariables (
IN CONST ACTIVE_OPTION *ActiveOption,
IN UINTN ActiveCount
)
{
UINTN Idx;
for (Idx = 0; Idx < ActiveCount; ++Idx) {
if (!ActiveOption[Idx].Appended) {
CHAR16 VariableName[9];
UnicodeSPrintAsciiFormat (VariableName, sizeof VariableName, "Boot%04x",
ActiveOption[Idx].BootOption->BootCurrent);
//
// "The space consumed by the deleted variable may not be available until
// the next power cycle", but that's good enough.
//
gRT->SetVariable (VariableName, &gEfiGlobalVariableGuid,
0, // Attributes, 0 means deletion
0, // DataSize, 0 means deletion
NULL // Data
);
}
}
}
/**
Set the boot order based on configuration retrieved from QEMU.
@ -1269,12 +1310,13 @@ SetBootOrderFromQemu (
BootOrder.Produced * sizeof (*BootOrder.Data),
BootOrder.Data
);
DEBUG ((
DEBUG_INFO,
"%a: setting BootOrder: %a\n",
__FUNCTION__,
Status == EFI_SUCCESS ? "success" : "error"
));
if (EFI_ERROR (Status)) {
DEBUG ((DEBUG_ERROR, "%a: setting BootOrder: %r\n", __FUNCTION__, Status));
goto ErrorFreeActiveOption;
}
DEBUG ((DEBUG_INFO, "%a: setting BootOrder: success\n", __FUNCTION__));
PruneBootVariables (ActiveOption, ActiveCount);
}
ErrorFreeActiveOption: