[PATCH v2 02/18] arm64: KVM: reset E2PB correctly in MDCR_EL2 when exiting the guest(VHE)

Andrew Murray
2019-12-20T14:33:45Z

From: Sudeep Holla <sudeep.holla@arm.com>

On VHE systems, the reset value for MDCR_EL2.E2PB=b00 which defaults
to profiling buffer using the EL2 stage 1 translations. However if the
guest are allowed to use profiling buffers changing E2PB settings, we
need to ensure we resume back MDCR_EL2.E2PB=b00. Currently we just
do bitwise '&' with MDCR_EL2_E2PB_MASK which will retain the value.

So fix it by clearing all the bits in E2PB.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Andrew Murray <andrew.murray@arm.com>
---
arch/arm64/kvm/hyp/switch.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index 72fbbd86eb5e..250f13910882 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -228,9 +228,7 @@ void deactivate_traps_vhe_put(void)
{
u64 mdcr_el2 = read_sysreg(mdcr_el2);

- mdcr_el2 &= MDCR_EL2_HPMN_MASK |
- MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT |
- MDCR_EL2_TPMS;
+ mdcr_el2 &= MDCR_EL2_HPMN_MASK | MDCR_EL2_TPMS;

write_sysreg(mdcr_el2, mdcr_el2);

--
2.21.0