linux-kernel - [PATCH v2 02/18] arm64: KVM: reset E2PB correctly in MDCR

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Date:   Fri, 20 Dec 2019 14:30:09 +0000
From:   Andrew Murray <andrew.murray@....com>
To:     Marc Zyngier <marc.zyngier@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>
Cc:     Sudeep Holla <sudeep.holla@....com>, kvmarm@...ts.cs.columbia.edu,
        linux-arm-kernel@...ts.infradead.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Mark Rutland <mark.rutland@....com>
Subject: [PATCH v2 02/18] arm64: KVM: reset E2PB correctly in MDCR_EL2 when exiting the guest(VHE)

From: Sudeep Holla <sudeep.holla@....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@....com>
Signed-off-by: Andrew Murray <andrew.murray@....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