[Xen-devel] [PATCH v4 01/29] ArmPkg: allow HYP timer interrupt to be omitted

[Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>]

The DT binding for the ARM generic timer describes the secure,
non-secure, virtual and hypervisor timer interrupts, respectively.
However, under virtualization, only the virtual timer is usable, and
the device tree may omit the hypervisor timer interrupt. (Other timer
interrupts cannot be omitted simply due to the fact that the virtual
timer is listed third)

Contributed-under: TianoCore Contribution Agreement 1.0
Reviewed-by: Olivier Martin <olivier.martin@xxxxxxx>
Reviewed-by: Laszlo Ersek <lersek@xxxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
 ArmPkg/Drivers/TimerDxe/TimerDxe.c                          | 14 +++++++++++---
 ArmPlatformPkg/ArmVirtualizationPkg/VirtFdtDxe/VirtFdtDxe.c |  6 +++---
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/ArmPkg/Drivers/TimerDxe/TimerDxe.c 
b/ArmPkg/Drivers/TimerDxe/TimerDxe.c
index d0a819fc2729..1169d426b255 100644
--- a/ArmPkg/Drivers/TimerDxe/TimerDxe.c
+++ b/ArmPkg/Drivers/TimerDxe/TimerDxe.c
@@ -369,7 +369,8 @@ TimerInitialize (
 {
   EFI_HANDLE  Handle = NULL;
   EFI_STATUS  Status;
-  UINTN TimerCtrlReg;
+  UINTN       TimerCtrlReg;
+  UINT32      TimerHypIntrNum;
 
   if (ArmIsArchTimerImplemented () == 0) {
     DEBUG ((EFI_D_ERROR, "ARM Architectural Timer is not available in the CPU, 
hence cann't use this Driver \n"));
@@ -395,8 +396,15 @@ TimerInitialize (
   Status = gInterrupt->RegisterInterruptSource (gInterrupt, PcdGet32 
(PcdArmArchTimerVirtIntrNum), TimerInterruptHandler);
   ASSERT_EFI_ERROR (Status);
 
-  Status = gInterrupt->RegisterInterruptSource (gInterrupt, PcdGet32 
(PcdArmArchTimerHypIntrNum), TimerInterruptHandler);
-  ASSERT_EFI_ERROR (Status);
+  //
+  // The hypervisor timer interrupt may be omitted by implementations that
+  // execute under virtualization.
+  //
+  TimerHypIntrNum = PcdGet32 (PcdArmArchTimerHypIntrNum);
+  if (TimerHypIntrNum != 0) {
+    Status = gInterrupt->RegisterInterruptSource (gInterrupt, TimerHypIntrNum, 
TimerInterruptHandler);
+    ASSERT_EFI_ERROR (Status);
+  }
 
   Status = gInterrupt->RegisterInterruptSource (gInterrupt, PcdGet32 
(PcdArmArchTimerSecIntrNum), TimerInterruptHandler);
   ASSERT_EFI_ERROR (Status);
diff --git a/ArmPlatformPkg/ArmVirtualizationPkg/VirtFdtDxe/VirtFdtDxe.c 
b/ArmPlatformPkg/ArmVirtualizationPkg/VirtFdtDxe/VirtFdtDxe.c
index 751864d4db9c..1d44f9ba02b3 100644
--- a/ArmPlatformPkg/ArmVirtualizationPkg/VirtFdtDxe/VirtFdtDxe.c
+++ b/ArmPlatformPkg/ArmVirtualizationPkg/VirtFdtDxe/VirtFdtDxe.c
@@ -274,7 +274,7 @@ InitializeVirtFdtDxe (
       //  hypervisor timers, in that order.
       //
       InterruptProp = fdt_getprop (DeviceTreeBase, Node, "interrupts", &Len);
-      ASSERT (Len == 48);
+      ASSERT (Len == 36 || Len == 48);
 
       SecIntrNum = fdt32_to_cpu (InterruptProp[0].Number)
                    + (InterruptProp[0].Type ? 16 : 0);
@@ -282,8 +282,8 @@ InitializeVirtFdtDxe (
                 + (InterruptProp[1].Type ? 16 : 0);
       VirtIntrNum = fdt32_to_cpu (InterruptProp[2].Number)
                     + (InterruptProp[2].Type ? 16 : 0);
-      HypIntrNum = fdt32_to_cpu (InterruptProp[3].Number)
-                   + (InterruptProp[3].Type ? 16 : 0);
+      HypIntrNum = Len < 48 ? 0 : fdt32_to_cpu (InterruptProp[3].Number)
+                                  + (InterruptProp[3].Type ? 16 : 0);
 
       DEBUG ((EFI_D_INFO, "Found Timer interrupts %d, %d, %d, %d\n",
         SecIntrNum, IntrNum, VirtIntrNum, HypIntrNum));
-- 
1.8.3.2


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