Hi Adrian, I believe there is already a similar patch on the mailing list at https://edk2.groups.io/g/devel/message/72596. This patch is pending review and tested-by. Can you check if this patch covers the problems you describe, please? Regards, Sami Mujawar From: devel@edk2.groups.io on behalf of Adrián Herrera via groups.io Date: Saturday, 24 April 2021 at 03:57 To: devel@edk2.groups.io Cc: Adrián Herrera Subject: [edk2-devel] [PATCH] ArmPkg/ArmGicLib: fix maximum interrupts supported The maximum number of interrupts supported is determined as 32 * (GICD_TYPER.ITLinesNumber + 1). When GICD_TYPER.ITLinesNumber = 0b11111, the maximum number of interrupts supported is 1024. However, both GICv2 and GICv3 reserve INTIDs 1020-1023 for special purposes. This results in runtime crashes because: (1) ArmGicLib functions do not guard against special interrupts. (2) ArmGicGetMaxNumInterrupts number includes special interrupts. (2) ArmGicV*Dxe relies on ArmGicGetMaxNumInterrupts, and thus programs special interrupts through ArmGicLib. ArmGicGetMaxNumInterrupts now does not include special interrupts, that is, it reports 1020 instead of 1024 when GICD_TYPER.ITLinesNumber = 0b11111. This avoids the overhead of guarding ArmGicLib functions while not requiring to modify the drivers code. Signed-off-by: Adrián Herrera --- ArmPkg/Drivers/ArmGic/ArmGicLib.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/ArmPkg/Drivers/ArmGic/ArmGicLib.c b/ArmPkg/Drivers/ArmGic/ArmGicLib.c index 6b01c88206..dff1401e9c 100644 --- a/ArmPkg/Drivers/ArmGic/ArmGicLib.c +++ b/ArmPkg/Drivers/ArmGic/ArmGicLib.c @@ -120,7 +120,10 @@ ArmGicGetMaxNumInterrupts ( IN INTN GicDistributorBase ) { - return 32 * ((MmioRead32 (GicDistributorBase + ARM_GIC_ICDICTR) & 0x1F) + 1); + UINT32 ITLinesNumber; + + ITLinesNumber = MmioRead32 (GicDistributorBase + ARM_GIC_ICDICTR) & 0x1F; + return MIN (32 * (ITLinesNumber+ 1), 1020); } VOID -- 2.30.0