From 5f05a72aed023e5824eebb2542b5397cb89188f4 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Wed, 28 Oct 2015 15:06:47 +0000 Subject: arm64: KVM: Move most of the fault decoding to C The fault decoding process (including computing the IPA in the case of a permission fault) would be much better done in C code, as we have a reasonable infrastructure to deal with the VHE/non-VHE differences. Let's move the whole thing to C, including the workaround for erratum 834220, and just patch the odd ESR_EL2 access remaining in hyp-entry.S. Reviewed-by: Christoffer Dall Acked-by: Catalin Marinas Signed-off-by: Marc Zyngier --- arch/arm64/kvm/hyp/switch.c | 85 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 85 insertions(+) (limited to 'arch/arm64/kvm/hyp/switch.c') diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c index 731f0a2ffee0..ecf5b05d1e16 100644 --- 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 . */ +#include #include #include "hyp.h" @@ -149,6 +150,86 @@ static void __hyp_text __vgic_restore_state(struct kvm_vcpu *vcpu) __vgic_call_restore_state()(vcpu); } +static bool __hyp_text __true_value(void) +{ + return true; +} + +static bool __hyp_text __false_value(void) +{ + return false; +} + +static hyp_alternate_select(__check_arm_834220, + __false_value, __true_value, + ARM64_WORKAROUND_834220); + +static bool __hyp_text __translate_far_to_hpfar(u64 far, u64 *hpfar) +{ + u64 par, tmp; + + /* + * Resolve the IPA the hard way using the guest VA. + * + * Stage-1 translation already validated the memory access + * rights. As such, we can use the EL1 translation regime, and + * don't have to distinguish between EL0 and EL1 access. + * + * We do need to save/restore PAR_EL1 though, as we haven't + * saved the guest context yet, and we may return early... + */ + par = read_sysreg(par_el1); + asm volatile("at s1e1r, %0" : : "r" (far)); + isb(); + + tmp = read_sysreg(par_el1); + write_sysreg(par, par_el1); + + if (unlikely(tmp & 1)) + return false; /* Translation failed, back to guest */ + + /* Convert PAR to HPFAR format */ + *hpfar = ((tmp >> 12) & ((1UL << 36) - 1)) << 4; + return true; +} + +static bool __hyp_text __populate_fault_info(struct kvm_vcpu *vcpu) +{ + u64 esr = read_sysreg_el2(esr); + u8 ec = esr >> ESR_ELx_EC_SHIFT; + u64 hpfar, far; + + vcpu->arch.fault.esr_el2 = esr; + + if (ec != ESR_ELx_EC_DABT_LOW && ec != ESR_ELx_EC_IABT_LOW) + return true; + + far = read_sysreg_el2(far); + + /* + * The HPFAR can be invalid if the stage 2 fault did not + * happen during a stage 1 page table walk (the ESR_EL2.S1PTW + * bit is clear) and one of the two following cases are true: + * 1. The fault was due to a permission fault + * 2. The processor carries errata 834220 + * + * Therefore, for all non S1PTW faults where we either have a + * permission fault or the errata workaround is enabled, we + * resolve the IPA using the AT instruction. + */ + if (!(esr & ESR_ELx_S1PTW) && + (__check_arm_834220()() || (esr & ESR_ELx_FSC_TYPE) == FSC_PERM)) { + if (!__translate_far_to_hpfar(far, &hpfar)) + return false; + } else { + hpfar = read_sysreg(hpfar_el2); + } + + vcpu->arch.fault.far_el2 = far; + vcpu->arch.fault.hpfar_el2 = hpfar; + return true; +} + static int __hyp_text __guest_run(struct kvm_vcpu *vcpu) { struct kvm_cpu_context *host_ctxt; @@ -180,9 +261,13 @@ static int __hyp_text __guest_run(struct kvm_vcpu *vcpu) __debug_restore_state(vcpu, kern_hyp_va(vcpu->arch.debug_ptr), guest_ctxt); /* Jump in the fire! */ +again: exit_code = __guest_enter(vcpu, host_ctxt); /* And we're baaack! */ + if (exit_code == ARM_EXCEPTION_TRAP && !__populate_fault_info(vcpu)) + goto again; + fp_enabled = __fpsimd_enabled(); __sysreg_save_guest_state(guest_ctxt); -- cgit