linux-kernel - [PATCH] KVM: arm64: Synchronize SMEN on vcpu schedule out

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Date:   Tue, 20 Dec 2022 18:50:24 +0800
From:   Dong Bo <dongbo4@...wei.com>
To:     <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <kvmarm@...ts.linux.dev>,
        <kvmarm@...ts.cs.columbia.edu>
CC:     Nianyao Tang <tangnianyao@...wei.com>,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Oliver Upton <oliver.upton@...ux.dev>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>
Subject: [PATCH] KVM: arm64: Synchronize SMEN on vcpu schedule out

From: Nianyao Tang <tangnianyao@...wei.com>

If we have VHE and need to reenable SME for host in
kvm_arch_vcpu_put_fp, CPACR.SMEN is modified from 0 to 1. Trap
control for reading SVCR is modified from enable to disable.
Synchronization is needed before reading SVCR later in
fpsimd_save, or it may cause sync exception which can not be
handled by host.

Cc: Marc Zyngier <maz@...nel.org>
Cc: James Morse <james.morse@....com>
Cc: Alexandru Elisei <alexandru.elisei@....com>
Cc: Suzuki K Poulose <suzuki.poulose@....com>
Cc: Oliver Upton <oliver.upton@...ux.dev>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will@...nel.org>
Signed-off-by: Nianyao Tang <tangnianyao@...wei.com>
---
 arch/arm64/kvm/fpsimd.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index 02dd7e9ebd39..f5799f571317 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -184,6 +184,7 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
 			sysreg_clear_set(CPACR_EL1,
 					 CPACR_EL1_SMEN_EL0EN,
 					 CPACR_EL1_SMEN_EL1EN);
+		isb();
 	}
 
 	if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED) {
-- 
1.8.3.1