On Tue, Aug 08, 2017 at 05:46:08PM +0100, James Morse wrote: > Make tpidr_el2 a cpu-offset for per-cpu variables in the same way the > host uses tpidr_el1. This lets tpidr_el{1,2} have the same value, and > on VHE they can be the same register. > > KVM calls hyp_panic() when anything unexpected happens. This may occur > while a guest owns the EL1 registers. KVM stashes the vcpu pointer in > tpidr_el2, which it uses to find the host context in order to restore > the host EL1 registers before parachuting into the host's panic(). > > The host context is a struct kvm_cpu_context allocated in the per-cpu > area, and mapped to hyp. Given the per-cpu offset for this CPU, this is > easy to find. Change hyp_panic() to take a pointer to the > struct kvm_cpu_context. Wrap these calls with an asm function that > retrieves the struct kvm_cpu_context from the host's per-cpu area. > > Copy the per-cpu offset from the hosts tpidr_el1 into tpidr_el2 during > kvm init. (Later patches will make this unnecessary for VHE hosts) > > We print out the vcpu pointer as part of the panic message. Add a back > reference to the 'running vcpu' in the host cpu context to preserve this. > > Signed-off-by: James Morse <james.mo...@arm.com> > --- > Changes since v1: > * Added a comment explaining how =kvm_host_cpu_state gets from a host-va > to a hyp va. > * Added the first paragraph to the commit message. > > arch/arm64/include/asm/kvm_host.h | 2 ++ > arch/arm64/kvm/hyp/hyp-entry.S | 12 ++++++++++++ > arch/arm64/kvm/hyp/s2-setup.c | 3 +++ > arch/arm64/kvm/hyp/switch.c | 25 +++++++++++++------------ > 4 files changed, 30 insertions(+), 12 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_host.h > b/arch/arm64/include/asm/kvm_host.h > index d68630007b14..7733492d9a35 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -191,6 +191,8 @@ struct kvm_cpu_context { > u64 sys_regs[NR_SYS_REGS]; > u32 copro[NR_COPRO_REGS]; > }; > + > + struct kvm_vcpu *__hyp_running_vcpu; > }; > > typedef struct kvm_cpu_context kvm_cpu_context_t; > diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S > index fce7cc507e0a..e4f37b9dd47c 100644 > --- a/arch/arm64/kvm/hyp/hyp-entry.S > +++ b/arch/arm64/kvm/hyp/hyp-entry.S > @@ -163,6 +163,18 @@ ENTRY(__hyp_do_panic) > eret > ENDPROC(__hyp_do_panic) > > +ENTRY(__hyp_panic) > + /* > + * '=kvm_host_cpu_state' is a host VA from the constant pool, it may > + * not be accessible by this address from EL2, hyp_panic() converts > + * it with kern_hyp_va() before use. > + */ > + ldr x0, =kvm_host_cpu_state > + mrs x1, tpidr_el2 > + add x0, x0, x1 > + b hyp_panic > +ENDPROC(__hyp_panic) > + > .macro invalid_vector label, target = __hyp_panic > .align 2 > \label: > diff --git a/arch/arm64/kvm/hyp/s2-setup.c b/arch/arm64/kvm/hyp/s2-setup.c > index b81f4091c909..eb401dbb285e 100644 > --- a/arch/arm64/kvm/hyp/s2-setup.c > +++ b/arch/arm64/kvm/hyp/s2-setup.c > @@ -84,5 +84,8 @@ u32 __hyp_text __init_stage2_translation(void) > > write_sysreg(val, vtcr_el2); > > + /* copy tpidr_el1 into tpidr_el2 for use by HYP */ > + write_sysreg(read_sysreg(tpidr_el1), tpidr_el2); > + > return parange; > } > diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c > index 945e79c641c4..235d615cee30 100644 > --- a/arch/arm64/kvm/hyp/switch.c > +++ b/arch/arm64/kvm/hyp/switch.c > @@ -286,9 +286,9 @@ int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu) > u64 exit_code; > > vcpu = kern_hyp_va(vcpu); > - write_sysreg(vcpu, tpidr_el2); > > host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context); > + host_ctxt->__hyp_running_vcpu = vcpu;
I'm fine with this for now, but eventually when we optimize KVM further we may want to avoid doing this in every world-switch. One option is to just set this pointer in vcpu_get and vcpu_load, but would it also be possible to use the kvm_arm_running_vcpu per-cpu array directly? > guest_ctxt = &vcpu->arch.ctxt; > > __sysreg_save_host_state(host_ctxt); > @@ -393,7 +393,8 @@ int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu) > > static const char __hyp_panic_string[] = "HYP panic:\nPS:%08llx PC:%016llx > ESR:%08llx\nFAR:%016llx HPFAR:%016llx PAR:%016llx\nVCPU:%p\n"; > > -static void __hyp_text __hyp_call_panic_nvhe(u64 spsr, u64 elr, u64 par) > +static void __hyp_text __hyp_call_panic_nvhe(u64 spsr, u64 elr, u64 par, > + struct kvm_vcpu *vcpu) > { > unsigned long str_va; > > @@ -407,35 +408,35 @@ static void __hyp_text __hyp_call_panic_nvhe(u64 spsr, > u64 elr, u64 par) > __hyp_do_panic(str_va, > spsr, elr, > read_sysreg(esr_el2), read_sysreg_el2(far), > - read_sysreg(hpfar_el2), par, > - (void *)read_sysreg(tpidr_el2)); > + read_sysreg(hpfar_el2), par, vcpu); > } > > -static void __hyp_text __hyp_call_panic_vhe(u64 spsr, u64 elr, u64 par) > +static void __hyp_text __hyp_call_panic_vhe(u64 spsr, u64 elr, u64 par, > + struct kvm_vcpu *vcpu) > { > panic(__hyp_panic_string, > spsr, elr, > read_sysreg_el2(esr), read_sysreg_el2(far), > - read_sysreg(hpfar_el2), par, > - (void *)read_sysreg(tpidr_el2)); > + read_sysreg(hpfar_el2), par, vcpu); > } > > static hyp_alternate_select(__hyp_call_panic, > __hyp_call_panic_nvhe, __hyp_call_panic_vhe, > ARM64_HAS_VIRT_HOST_EXTN); > > -void __hyp_text __noreturn __hyp_panic(void) > +void __hyp_text __noreturn hyp_panic(struct kvm_cpu_context *__host_ctxt) > { > + struct kvm_vcpu *vcpu = NULL; > + > u64 spsr = read_sysreg_el2(spsr); > u64 elr = read_sysreg_el2(elr); > u64 par = read_sysreg(par_el1); > > if (read_sysreg(vttbr_el2)) { > - struct kvm_vcpu *vcpu; > struct kvm_cpu_context *host_ctxt; > > - vcpu = (struct kvm_vcpu *)read_sysreg(tpidr_el2); > - host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context); > + host_ctxt = kern_hyp_va(__host_ctxt); > + vcpu = host_ctxt->__hyp_running_vcpu; > __timer_save_state(vcpu); > __deactivate_traps(vcpu); > __deactivate_vm(vcpu); > @@ -443,7 +444,7 @@ void __hyp_text __noreturn __hyp_panic(void) > } > > /* Call panic for real */ > - __hyp_call_panic()(spsr, elr, par); > + __hyp_call_panic()(spsr, elr, par, vcpu); > > unreachable(); > } > -- > 2.13.3 > Reviewed-by: Christoffer Dall <cd...@linaro.org> _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm