Commit d10bcd47 authored Sep 02, 2015 by Will Deacon

arm64: head.S: initialise mdcr_el2 in el2_setup



When entering the kernel at EL2, we fail to initialise the MDCR_EL2
register which controls debug access and PMU capabilities at EL1.

This patch ensures that the register is initialised so that all traps
are disabled and all the PMU counters are available to the host. When a
guest is scheduled, KVM takes care to configure trapping appropriately.

Cc: <stable@vger.kernel.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

parent 2314ee4d

arch/arm64/kernel/head.S

+5 −0

Original line number	Diff line number	Diff line
		@@ -523,6 +523,11 @@ CPU_LE( movk x0, #0x30d0, lsl #16 ) // Clear EE and E0E on LE systems
		msr hstr_el2, xzr // Disable CP15 traps to EL2
		#endif

		/* EL2 debug */
		mrs x0, pmcr_el0 // Disable debug access traps
		ubfx x0, x0, #11, #5 // to EL2 and allow access to
		msr mdcr_el2, x0 // all PMU counters from EL1

		/* Stage-2 translation */
		msr vttbr_el2, xzr