linux-kernel - [PATCH 4.19 040/280] arm/arm64: KVM: Dont panic on failure to properly reset system registers

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Date:   Fri, 22 Mar 2019 12:13:13 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Marc Zyngier <marc.zyngier@....com>,
        Christoffer Dall <christoffer.dall@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 040/280] arm/arm64: KVM: Dont panic on failure to properly reset system registers

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 20589c8cc47dce5854c8bf1b44a9fc63d798d26d ]

Failing to properly reset system registers is pretty bad. But not
quite as bad as bringing the whole machine down... So warn loudly,
but slightly more gracefully.

Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Acked-by: Christoffer Dall <christoffer.dall@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm/kvm/coproc.c     | 4 ++--
 arch/arm64/kvm/sys_regs.c | 8 +++++---
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/arm/kvm/coproc.c b/arch/arm/kvm/coproc.c
index cb094e55dc5f..fd6cde23bb5d 100644
--- a/arch/arm/kvm/coproc.c
+++ b/arch/arm/kvm/coproc.c
@@ -1450,6 +1450,6 @@ void kvm_reset_coprocs(struct kvm_vcpu *vcpu)
 	reset_coproc_regs(vcpu, table, num);
 
 	for (num = 1; num < NR_CP15_REGS; num++)
-		if (vcpu_cp15(vcpu, num) == 0x42424242)
-			panic("Didn't reset vcpu_cp15(vcpu, %zi)", num);
+		WARN(vcpu_cp15(vcpu, num) == 0x42424242,
+		     "Didn't reset vcpu_cp15(vcpu, %zi)", num);
 }
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 22fbbdbece3c..fe18e68f9a20 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -2586,7 +2586,9 @@ void kvm_reset_sys_regs(struct kvm_vcpu *vcpu)
 	table = get_target_table(vcpu->arch.target, true, &num);
 	reset_sys_reg_descs(vcpu, table, num);
 
-	for (num = 1; num < NR_SYS_REGS; num++)
-		if (__vcpu_sys_reg(vcpu, num) == 0x4242424242424242)
-			panic("Didn't reset __vcpu_sys_reg(%zi)", num);
+	for (num = 1; num < NR_SYS_REGS; num++) {
+		if (WARN(__vcpu_sys_reg(vcpu, num) == 0x4242424242424242,
+			 "Didn't reset __vcpu_sys_reg(%zi)\n", num))
+			break;
+	}
 }
-- 
2.19.1