4.9-stable review patch. If anyone has any objections, please let me know.
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From: Marc Zyngier marc.zyngier@arm.com
commit 55e3748e8902ff641e334226bdcb432f9a5d78d3 upstream.
In order to offer ARCH_WORKAROUND_2 support to guests, we need a bit of infrastructure.
Let's add a flag indicating whether or not the guest uses SSBD mitigation. Depending on the state of this flag, allow KVM to disable ARCH_WORKAROUND_2 before entering the guest, and enable it when exiting it.
Reviewed-by: Christoffer Dall christoffer.dall@arm.com Reviewed-by: Mark Rutland mark.rutland@arm.com Signed-off-by: Marc Zyngier marc.zyngier@arm.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Marc Zyngier marc.zyngier@arm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm/include/asm/kvm_mmu.h | 5 +++++ arch/arm/kvm/arm.c | 6 ++++++ arch/arm64/include/asm/kvm_asm.h | 3 +++ arch/arm64/include/asm/kvm_host.h | 3 +++ arch/arm64/include/asm/kvm_mmu.h | 24 ++++++++++++++++++++++++ arch/arm64/kvm/hyp/switch.c | 38 ++++++++++++++++++++++++++++++++++++++ 6 files changed, 79 insertions(+)
--- a/arch/arm/include/asm/kvm_mmu.h +++ b/arch/arm/include/asm/kvm_mmu.h @@ -256,6 +256,11 @@ static inline int kvm_map_vectors(void) return 0; }
+static inline int hyp_map_aux_data(void) +{ + return 0; +} + #endif /* !__ASSEMBLY__ */
#endif /* __ARM_KVM_MMU_H__ */ --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -1367,6 +1367,12 @@ static int init_hyp_mode(void) } }
+ err = hyp_map_aux_data(); + if (err) { + kvm_err("Cannot map host auxilary data: %d\n", err); + goto out_err; + } + kvm_info("Hyp mode initialized successfully\n");
return 0; --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -33,6 +33,9 @@ #define KVM_ARM64_DEBUG_DIRTY_SHIFT 0 #define KVM_ARM64_DEBUG_DIRTY (1 << KVM_ARM64_DEBUG_DIRTY_SHIFT)
+#define VCPU_WORKAROUND_2_FLAG_SHIFT 0 +#define VCPU_WORKAROUND_2_FLAG (_AC(1, UL) << VCPU_WORKAROUND_2_FLAG_SHIFT) + /* Translate a kernel address of @sym into its equivalent linear mapping */ #define kvm_ksym_ref(sym) \ ({ \ --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -213,6 +213,9 @@ struct kvm_vcpu_arch { /* Exception Information */ struct kvm_vcpu_fault_info fault;
+ /* State of various workarounds, see kvm_asm.h for bit assignment */ + u64 workaround_flags; + /* Guest debug state */ u64 debug_flags;
--- a/arch/arm64/include/asm/kvm_mmu.h +++ b/arch/arm64/include/asm/kvm_mmu.h @@ -387,5 +387,29 @@ static inline int kvm_map_vectors(void) } #endif
+#ifdef CONFIG_ARM64_SSBD +DECLARE_PER_CPU_READ_MOSTLY(u64, arm64_ssbd_callback_required); + +static inline int hyp_map_aux_data(void) +{ + int cpu, err; + + for_each_possible_cpu(cpu) { + u64 *ptr; + + ptr = per_cpu_ptr(&arm64_ssbd_callback_required, cpu); + err = create_hyp_mappings(ptr, ptr + 1, PAGE_HYP); + if (err) + return err; + } + return 0; +} +#else +static inline int hyp_map_aux_data(void) +{ + return 0; +} +#endif + #endif /* __ASSEMBLY__ */ #endif /* __ARM64_KVM_MMU_H__ */ --- a/arch/arm64/kvm/hyp/switch.c +++ b/arch/arm64/kvm/hyp/switch.c @@ -15,6 +15,7 @@ * along with this program. If not, see http://www.gnu.org/licenses/. */
+#include <linux/arm-smccc.h> #include <linux/types.h> #include <linux/jump_label.h> #include <uapi/linux/psci.h> @@ -267,6 +268,39 @@ static void __hyp_text __skip_instr(stru write_sysreg_el2(*vcpu_pc(vcpu), elr); }
+static inline bool __hyp_text __needs_ssbd_off(struct kvm_vcpu *vcpu) +{ + if (!cpus_have_cap(ARM64_SSBD)) + return false; + + return !(vcpu->arch.workaround_flags & VCPU_WORKAROUND_2_FLAG); +} + +static void __hyp_text __set_guest_arch_workaround_state(struct kvm_vcpu *vcpu) +{ +#ifdef CONFIG_ARM64_SSBD + /* + * The host runs with the workaround always present. If the + * guest wants it disabled, so be it... + */ + if (__needs_ssbd_off(vcpu) && + __hyp_this_cpu_read(arm64_ssbd_callback_required)) + arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_2, 0, NULL); +#endif +} + +static void __hyp_text __set_host_arch_workaround_state(struct kvm_vcpu *vcpu) +{ +#ifdef CONFIG_ARM64_SSBD + /* + * If the guest has disabled the workaround, bring it back on. + */ + if (__needs_ssbd_off(vcpu) && + __hyp_this_cpu_read(arm64_ssbd_callback_required)) + arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_2, 1, NULL); +#endif +} + int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu) { struct kvm_cpu_context *host_ctxt; @@ -297,6 +331,8 @@ int __hyp_text __kvm_vcpu_run(struct kvm __sysreg_restore_guest_state(guest_ctxt); __debug_restore_state(vcpu, kern_hyp_va(vcpu->arch.debug_ptr), guest_ctxt);
+ __set_guest_arch_workaround_state(vcpu); + /* Jump in the fire! */ again: exit_code = __guest_enter(vcpu, host_ctxt); @@ -339,6 +375,8 @@ again: } }
+ __set_host_arch_workaround_state(vcpu); + fp_enabled = __fpsimd_enabled();
__sysreg_save_guest_state(guest_ctxt);