Commit c97e166e authored by James Morse's avatar James Morse Committed by Catalin Marinas
Browse files

KVM: arm64: Change hyp_panic()s dependency on tpidr_el2 



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: default avatarJames Morse <james.morse@arm.com>
Reviewed-by: default avatarChristoffer Dall <cdall@linaro.org>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 36989e7f

arch/arm64/include/asm/kvm_host.h

+2 −0
Original line number Diff line number Diff line
@@ -192,6 +192,8 @@ 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;

arch/arm64/kvm/hyp/hyp-entry.S

+12 −0
Original line number Diff line number Diff line
@@ -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:

arch/arm64/kvm/hyp/s2-setup.c

+3 −0
Original line number Diff line number Diff line
@@ -86,5 +86,8 @@ 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;

}

arch/arm64/kvm/hyp/switch.c

+13 −12
Original line number Diff line number Diff line
@@ -306,9 +306,9 @@ 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;

	guest_ctxt = &vcpu->arch.ctxt;



	__sysreg_save_host_state(host_ctxt);
@@ -443,7 +443,8 @@ again: 


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;
@@ -457,35 +458,35 @@ 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_disable_traps(vcpu);

		__deactivate_traps(vcpu);

		__deactivate_vm(vcpu);
@@ -493,7 +494,7 @@ 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();

}

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