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[2/6] KVM: arm64: Clean up SMC64 PSCI filtering for AArch32 guests

Message ID 20210819223640.3564975-3-oupton@google.com (mailing list archive)
State New, archived
Headers show
Series KVM: arm64: Implement PSCI SYSTEM_SUSPEND support | expand

Commit Message

Oliver Upton Aug. 19, 2021, 10:36 p.m. UTC 
The only valid calling SMC calling convention from an AArch32 state is
SMC32. Disallow any PSCI function that sets the SMC64 function ID bit
when called from AArch32 rather than comparing against known SMC64 PSCI
functions.

Signed-off-by: Oliver Upton <oupton@google.com>
---
 arch/arm64/kvm/psci.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)
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Patch

diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
index d46842f45b0a..310b9cb2b32b 100644
--- a/arch/arm64/kvm/psci.c
+++ b/arch/arm64/kvm/psci.c
@@ -208,15 +208,11 @@  static void kvm_psci_narrow_to_32bit(struct kvm_vcpu *vcpu)
 
 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;
-	}
+	/*
+	 * Prevent 32 bit guests from calling 64 bit PSCI functions.
+	 */
+	if ((fn & PSCI_0_2_64BIT) && vcpu_mode_is_32bit(vcpu))
+		return PSCI_RET_NOT_SUPPORTED;
 
 	return 0;
 }