On 2021-01-27 08:55, Anshuman Khandual wrote:
From: Suzuki K Poulose <[email protected]>
When the kernel is booted at EL2 in a nvhe configuration,
enable the TRBE access to the EL1. The EL1 still can't trace
EL2, unless EL2 permits explicitly via TRFCR_EL2.E2TRE.
Cc: Will Deacon <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: Mark Rutland <[email protected]>
cc: Anshuman Khandual <[email protected]>
Signed-off-by: Suzuki K Poulose <[email protected]>
Signed-off-by: Anshuman Khandual <[email protected]>
Acked-by: Marc Zyngier <[email protected]>
One comment below, though:
---
arch/arm64/include/asm/el2_setup.h | 19 +++++++++++++++++++
arch/arm64/include/asm/kvm_arm.h | 2 ++
2 files changed, 21 insertions(+)
diff --git a/arch/arm64/include/asm/el2_setup.h
b/arch/arm64/include/asm/el2_setup.h
index a7f5a1b..05ecce9 100644
--- a/arch/arm64/include/asm/el2_setup.h
+++ b/arch/arm64/include/asm/el2_setup.h
@@ -72,6 +72,25 @@
.endif
3:
+
+.ifeqs "\mode", "nvhe"
+ /*
+ * If the Trace Buffer is available, allow
+ * the EL1 to own it. Note that EL1 cannot
+ * trace the EL2, as it is prevented by
+ * TRFCR_EL2.E2TRE == 0.
+ */
+ ubfx x0, x1, #ID_AA64DFR0_TRBE_SHIFT, #4
+ cbz x0, 1f
+
+ mrs_s x0, SYS_TRBIDR_EL1
+ and x0, x0, TRBIDR_PROG
+ cbnz x0, 1f
+ mov x0, #(MDCR_EL2_E2TB_EL1_OWN << MDCR_EL2_E2TB_SHIFT)
+ orr x2, x2, x0
+.endif
+
+1:
Note that this will (badly) conflict with the late-VHE patches[1],
where this code path has been reworked.
Thanks,
M.
[1] https://lore.kernel.org/r/[email protected]
--
Jazz is not dead. It just smells funny...
