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Wed, 01 Apr 2020 17:58:30 +0100 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org Subject: [PATCH 2/2] KVM: arm64: PSCI: Forbid 64bit functions for 32bit guests Date: Wed, 1 Apr 2020 17:58:16 +0100 Message-Id: <20200401165816.530281-3-maz@kernel.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200401165816.530281-1-maz@kernel.org> References: <20200401165816.530281-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, Christoffer.Dall@arm.com, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200401_095835_037859_522C2243 X-CRM114-Status: GOOD ( 13.99 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: James Morse , Christoffer Dall , Julien Thierry , Suzuki K Poulose Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Implementing (and even advertising) 64bit PSCI functions to 32bit guests is at least a bit odd, if not altogether violating the spec which says ("5.2.1 Register usage in arguments and return values"): "Adherence to the SMC Calling Conventions implies that any AArch32 caller of an SMC64 function will get a return code of 0xFFFFFFFF(int32). This matches the NOT_SUPPORTED error code used in PSCI" Tighten the implementation by pretending these functions are not there for 32bit guests. Signed-off-by: Marc Zyngier --- virt/kvm/arm/psci.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c index 69ff4a51ceb5..122795cdd984 100644 --- a/virt/kvm/arm/psci.c +++ b/virt/kvm/arm/psci.c @@ -199,6 +199,21 @@ static void kvm_psci_narrow_to_32bit(struct kvm_vcpu *vcpu) vcpu_set_reg(vcpu, i, (u32)vcpu_get_reg(vcpu, i)); } +static unsigned long kvm_psci_check_allowed_function(struct kvm_vcpu *vcpu, u32 fn) +{ + switch(fn) { + case PSCI_0_2_FN64_CPU_SUSPEND: + case PSCI_0_2_FN64_CPU_ON: + case PSCI_0_2_FN64_AFFINITY_INFO: + /* Disallow these functions for 32bit guests */ + if (vcpu_mode_is_32bit(vcpu)) + return PSCI_RET_NOT_SUPPORTED; + break; + } + + return 0; +} + static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) { struct kvm *kvm = vcpu->kvm; @@ -206,6 +221,10 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) unsigned long val; int ret = 1; + val = kvm_psci_check_allowed_function(vcpu, psci_fn); + if (val) + goto out; + switch (psci_fn) { case PSCI_0_2_FN_PSCI_VERSION: /* @@ -273,6 +292,7 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) break; } +out: smccc_set_retval(vcpu, val, 0, 0, 0); return ret; } @@ -290,6 +310,10 @@ static int kvm_psci_1_0_call(struct kvm_vcpu *vcpu) break; case PSCI_1_0_FN_PSCI_FEATURES: feature = smccc_get_arg1(vcpu); + val = kvm_psci_check_allowed_function(vcpu, feature); + if (val) + break; + switch(feature) { case PSCI_0_2_FN_PSCI_VERSION: case PSCI_0_2_FN_CPU_SUSPEND: -- 2.25.0 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel