diff mbox series

[RFC,v3,12/16] KVM: arm64: VHE: Clear MDCR_EL2.E2PB in vcpu_put()

Message ID 20201027172705.15181-13-alexandru.elisei@arm.com (mailing list archive)
State New, archived
Headers show
Series KVM: arm64: Add Statistical Profiling Extension (SPE) support | expand

Commit Message

Alexandru Elisei Oct. 27, 2020, 5:27 p.m. UTC 
From: Sudeep Holla <sudeep.holla@arm.com>

On VHE systems, the kernel executes at EL2 and configures the profiling
buffer to use the EL2&0 translation regime and to trap accesses from the
guest by clearing MDCR_EL2.E2PB. In vcpu_put(), KVM does a bitwise or with
the E2PB mask, preserving its value. This has been correct so far, since
MDCR_EL2.E2B has the same value (0b00) for all VMs.

However, this will change when KVM enables support for SPE in guests. For
such guests KVM will configure the profiling buffer to use the EL1&0
translation regime, a setting that is obviously undesirable to be preserved
for the host running at EL2. Let's avoid this situation by explicitly
clearing E2PB in vcpu_put().

[ Alexandru E: Rebased on top of 5.10-rc1, reworded commit ]

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
 arch/arm64/kvm/hyp/vhe/switch.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
index fe69de16dadc..3f4db1fa388b 100644
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -97,9 +97,7 @@  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);