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: James Morse <james.morse@arm.com>
Reviewed-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index ea6cb5b24258be29f39507c39d526ea7e52c7c30..7ee72b402907dca17f997a0877d0c222e179256a 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -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;

diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
index fce7cc507e0a686987f705db69dc48d64caff6e4..e4f37b9dd47c05eb6013db98383e5f0c6f1348ea 100644 (file)
--- 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 603e1ee83e8924708be61c9d92416d126d9887f2..74306c33a6deb1736f0bb02c19952633d8a4c1d3 100644 (file)
--- a/arch/arm64/kvm/hyp/s2-setup.c
+++ b/arch/arm64/kvm/hyp/s2-setup.c
@@ -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;
 }

diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index 170e1917f83cce007de2a23083b31ec8a3a77980..324f4202cdd50a35573d3a9aa12ac28df8a97327 100644 (file)
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -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();
 }