The SPE architecture requires each exception level to enable access
to the SPE controls for the exception level below it, since additional
context-switch logic may be required to handle the buffer safely.
This patch allows EL1 (host) access to the SPE controls when entered at
EL2.
Cc: Marc Zyngier <marc.zyng...@arm.com>
Signed-off-by: Will Deacon <will.dea...@arm.com>
---
arch/arm64/kernel/head.S | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 4b1abac3485a..6a97831dcf3b 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -592,8 +592,8 @@ CPU_LE( movk x0, #0x30d0, lsl #16 ) //
Clear EE and E0E on LE systems
#endif
/* EL2 debug */
- mrs x0, id_aa64dfr0_el1 // Check ID_AA64DFR0_EL1 PMUVer
- sbfx x0, x0, #8, #4
+ mrs x1, id_aa64dfr0_el1 // Check ID_AA64DFR0_EL1 PMUVer
+ sbfx x0, x1, #8, #4
cmp x0, #1
b.lt 4f // Skip if no PMU present
mrs x0, pmcr_el0 // Disable debug access traps
@@ -601,6 +601,16 @@ CPU_LE( movk x0, #0x30d0, lsl #16 ) //
Clear EE and E0E on LE systems
4:
csel x0, xzr, x0, lt // all PMU counters from EL1
msr mdcr_el2, x0 // (if they exist)
+ /* Statistical profiling */
+ ubfx x0, x1, #32, #4 // Check ID_AA64DFR0_EL1 PMSVer
+ cbz x0, 5f // Skip if SPE not present
+ mrs x0, mdcr_el2 // Preserve HPMN field
+ cmp x2, xzr // If VHE is not enabled,
+ mov x1, #3 // use EL1&0 translations,
+ cinc x1, x1, ne // otherwise use EL2 and
+ bfi x0, x1, #12, #3 // enable/disable access
+ msr mdcr_el2, x0 // traps accordingly.
+5:
/* Stage-2 translation */
msr vttbr_el2, xzr
--
2.1.4
