From f19f6644a5433cfae8a068445b149bc2247c1445 Mon Sep 17 00:00:00 2001 From: David Brazdil Date: Wed, 2 Dec 2020 18:41:22 +0000 Subject: [PATCH] KVM: arm64: Fix EL2 mode availability checks With protected nVHE hyp code interception host's PSCI SMCs, the host starts seeing new CPUs boot in EL1 instead of EL2. The kernel logic that keeps track of the boot mode needs to be adjusted. Add a static key enabled if KVM protected mode initialization is successful. When the key is enabled, is_hyp_mode_available continues to report `true` because its users either treat it as a check whether KVM will be / was initialized, or whether stub HVCs can be made (eg. hibernate). is_hyp_mode_mismatched is changed to report `false` when the key is enabled. That's because all cores' modes matched at the point of KVM init and KVM will not allow cores not present at init to boot. That said, the function is never used after KVM is initialized. Signed-off-by: David Brazdil Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20201202184122.26046-27-dbrazdil@google.com --- arch/arm64/include/asm/virt.h | 18 ++++++++++++++++++ arch/arm64/kvm/arm.c | 9 ++++++--- 2 files changed, 24 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h index eb81dcc220b65..ee6a48df89d9c 100644 --- a/arch/arm64/include/asm/virt.h +++ b/arch/arm64/include/asm/virt.h @@ -65,9 +65,19 @@ extern u32 __boot_cpu_mode[2]; void __hyp_set_vectors(phys_addr_t phys_vector_base); void __hyp_reset_vectors(void); +DECLARE_STATIC_KEY_FALSE(kvm_protected_mode_initialized); + /* Reports the availability of HYP mode */ static inline bool is_hyp_mode_available(void) { + /* + * If KVM protected mode is initialized, all CPUs must have been booted + * in EL2. Avoid checking __boot_cpu_mode as CPUs now come up in EL1. + */ + if (IS_ENABLED(CONFIG_KVM) && + static_branch_likely(&kvm_protected_mode_initialized)) + return true; + return (__boot_cpu_mode[0] == BOOT_CPU_MODE_EL2 && __boot_cpu_mode[1] == BOOT_CPU_MODE_EL2); } @@ -75,6 +85,14 @@ static inline bool is_hyp_mode_available(void) /* Check if the bootloader has booted CPUs in different modes */ static inline bool is_hyp_mode_mismatched(void) { + /* + * If KVM protected mode is initialized, all CPUs must have been booted + * in EL2. Avoid checking __boot_cpu_mode as CPUs now come up in EL1. + */ + if (IS_ENABLED(CONFIG_KVM) && + static_branch_likely(&kvm_protected_mode_initialized)) + return false; + return __boot_cpu_mode[0] != __boot_cpu_mode[1]; } diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 7d162a2961417..fadcc94931f99 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -48,6 +48,7 @@ __asm__(".arch_extension virt"); #endif static enum kvm_mode kvm_mode = KVM_MODE_DEFAULT; +DEFINE_STATIC_KEY_FALSE(kvm_protected_mode_initialized); DECLARE_KVM_HYP_PER_CPU(unsigned long, kvm_hyp_vector); @@ -1848,12 +1849,14 @@ int kvm_arch_init(void *opaque) if (err) goto out_hyp; - if (is_protected_kvm_enabled()) + if (is_protected_kvm_enabled()) { + static_branch_enable(&kvm_protected_mode_initialized); kvm_info("Protected nVHE mode initialized successfully\n"); - else if (in_hyp_mode) + } else if (in_hyp_mode) { kvm_info("VHE mode initialized successfully\n"); - else + } else { kvm_info("Hyp mode initialized successfully\n"); + } return 0; -- 2.30.2