[PATCH v2 2/2] KVM: arm64: Trap access to SMPRI_EL1 and TPIDR2 in VHE mode

From: Mark Brown <broonie@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>
Cc: Peter Maydell <peter.maydell@linaro.org>,
	Richard Henderson <richard.henderson@linaro.org>,
	Vincent Donnefort <vdonnefort@google.com>,
	James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
	Mark Brown <broonie@kernel.org>,
	stable@vger.kernel.org
Subject: [PATCH v2 2/2] KVM: arm64: Trap access to SMPRI_EL1 and TPIDR2 in VHE mode
Date: Tue,  1 Nov 2022 11:27:15 +0000	[thread overview]
Message-ID: <20221101112716.52035-3-broonie@kernel.org> (raw)
In-Reply-To: <20221101112716.52035-1-broonie@kernel.org>

On systems with SME access to the SMPRI_EL1 priority management register is
controlled by the nSMPRI_EL1 fine grained trap and TPIDR2_EL0 is controlled
by nTPIDR2_EL0. We manage these traps in nVHE mode but do not do so when in
VHE mode, add the required management.

Without this these registers could be used as side channels where implemented.

Fixes: 861262ab8627 ("KVM: arm64: Handle SME host state when running guests")
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
---
 arch/arm64/kvm/hyp/vhe/switch.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
index 7acb87eaa092..9dac3a1a85f7 100644
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -63,10 +63,20 @@ static void __activate_traps(struct kvm_vcpu *vcpu)
 		__activate_traps_fpsimd32(vcpu);
 	}
 
-	if (cpus_have_final_cap(ARM64_SME))
+	if (cpus_have_final_cap(ARM64_SME)) {
 		write_sysreg(read_sysreg(sctlr_el2) & ~SCTLR_ELx_ENTP2,
 			     sctlr_el2);
 
+		sysreg_clear_set_s(SYS_HFGRTR_EL2,
+				   HFGxTR_EL2_nSMPRI_EL1_MASK |
+				   HFGxTR_EL2_nTPIDR2_EL0_MASK,
+				   0);
+		sysreg_clear_set_s(SYS_HFGWTR_EL2,
+				   HFGxTR_EL2_nSMPRI_EL1_MASK |
+				   HFGxTR_EL2_nTPIDR2_EL0_MASK,
+				   0);
+	}
+
 	write_sysreg(val, cpacr_el1);
 
 	write_sysreg(__this_cpu_read(kvm_hyp_vector), vbar_el1);
@@ -88,9 +98,21 @@ static void __deactivate_traps(struct kvm_vcpu *vcpu)
 	 */
 	asm(ALTERNATIVE("nop", "isb", ARM64_WORKAROUND_SPECULATIVE_AT));
 
-	if (cpus_have_final_cap(ARM64_SME))
+	if (cpus_have_final_cap(ARM64_SME)) {
+		/*
+		 * Enable access to SMPRI_EL1 - we don't need to
+		 * control nTPIDR2_EL0 in VHE mode.
+		 */
+		sysreg_clear_set_s(SYS_HFGRTR_EL2, 0,
+				   HFGxTR_EL2_nSMPRI_EL1_MASK |
+				   HFGxTR_EL2_nTPIDR2_EL0_MASK);
+		sysreg_clear_set_s(SYS_HFGWTR_EL2, 0,
+				   HFGxTR_EL2_nSMPRI_EL1_MASK |
+				   HFGxTR_EL2_nTPIDR2_EL0_MASK);
+
 		write_sysreg(read_sysreg(sctlr_el2) | SCTLR_ELx_ENTP2,
 			     sctlr_el2);
+	}
 
 	write_sysreg(CPACR_EL1_DEFAULT, cpacr_el1);
 
-- 
2.30.2


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