@@ -198,6 +198,16 @@ extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ];
ldr \vcpu, [\ctxt, #HOST_CONTEXT_VCPU]
.endm
+.macro get_loaded_vcpu vcpu, ctxt
+ hyp_adr_this_cpu \ctxt, kvm_hyp_ctxt, \vcpu
+ ldr \vcpu, [\ctxt, #HOST_CONTEXT_VCPU]
+.endm
+
+.macro set_loaded_vcpu vcpu, ctxt, tmp
+ hyp_adr_this_cpu \ctxt, kvm_hyp_ctxt, \tmp
+ str \vcpu, [\ctxt, #HOST_CONTEXT_VCPU]
+.endm
+
#endif
#endif /* __ARM_KVM_ASM_H__ */
@@ -86,6 +86,8 @@ alternative_else_nop_endif
ret
1:
+ set_loaded_vcpu x0, x1, x2
+
add x29, x0, #VCPU_CONTEXT
// Macro ptrauth_switch_to_guest format:
@@ -116,6 +118,26 @@ alternative_else_nop_endif
eret
sb
+SYM_INNER_LABEL(__guest_exit_panic, SYM_L_GLOBAL)
+ // x2-x29,lr: vcpu regs
+ // vcpu x0-x1 on the stack
+
+ // If the hyp context is loaded, go straight to hyp_panic
+ get_loaded_vcpu x0, x1
+ cbz x0, hyp_panic
+
+ // The hyp context is saved so make sure it is restored to allow
+ // hyp_panic to run at hyp and, subsequently, panic to run in the host.
+ // This makes use of __guest_exit to avoid duplication but sets the
+ // return address to tail call into hyp_panic. As a side effect, the
+ // current state is saved to the guest context but it will only be
+ // accurate if the guest had been completely restored.
+ hyp_adr_this_cpu x0, kvm_hyp_ctxt, x1
+ adr x1, hyp_panic
+ str x1, [x0, #CPU_XREG_OFFSET(30)]
+
+ get_vcpu_ptr x1, x0
+
SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL)
// x0: return code
// x1: vcpu
@@ -163,6 +185,8 @@ SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL)
// Now restore the hyp regs
restore_callee_saved_regs x2
+ set_loaded_vcpu xzr, x1, x2
+
alternative_if ARM64_HAS_RAS_EXTN
// If we have the RAS extensions we can consume a pending error
// without an unmask-SError and isb. The ESB-instruction consumed any
@@ -96,7 +96,7 @@ el2_sync:
/* if this was something else, then panic! */
tst x0, #PSR_IL_BIT
- b.eq hyp_panic
+ b.eq __guest_exit_panic
/* Let's attempt a recovery from the illegal exception return */
get_vcpu_ptr x1, x0
@@ -105,8 +105,6 @@ el2_sync:
el2_error:
- ldp x0, x1, [sp], #16
-
/*
* Only two possibilities:
* 1) Either we come from the exit path, having just unmasked
@@ -124,12 +122,13 @@ el2_error:
cmp x0, x1
adr x1, abort_guest_exit_end
ccmp x0, x1, #4, ne
- b.ne hyp_panic
+ b.ne __guest_exit_panic
+ ldp x0, x1, [sp], #16
mov x0, #(1 << ARM_EXIT_WITH_SERROR_BIT)
eret
sb
-.macro invalid_vector label, target = hyp_panic
+.macro invalid_vector label, target = __guest_exit_panic
.align 2
SYM_CODE_START(\label)
b \target
@@ -170,10 +169,9 @@ check_preamble_length 661b, 662b
.macro invalid_vect target
.align 7
661:
- b \target
nop
+ stp x0, x1, [sp, #-16]!
662:
- ldp x0, x1, [sp], #16
b \target
check_preamble_length 661b, 662b
@@ -72,6 +72,11 @@ SYM_FUNC_END(__hyp_do_panic)
.macro invalid_host_vect
.align 7
+ /* If a guest is loaded, panic out of it. */
+ stp x0, x1, [sp, #-16]!
+ get_loaded_vcpu x0, x1
+ cbnz x0, __guest_exit_panic
+ add sp, sp, #16
b hyp_panic
.endm
If the guest context is loaded when a panic is triggered, restore the hyp context so e.g. the shadow call stack works when hyp_panic() is called and SP_EL0 is valid when the host's panic() is called. Use the hyp context's __hyp_running_vcpu field to track when hyp transitions to and from the guest vcpu so the exception handlers know whether the context needs to be restored. Signed-off-by: Andrew Scull <ascull@google.com> --- arch/arm64/include/asm/kvm_asm.h | 10 ++++++++++ arch/arm64/kvm/hyp/entry.S | 24 ++++++++++++++++++++++++ arch/arm64/kvm/hyp/hyp-entry.S | 12 +++++------- arch/arm64/kvm/hyp/nvhe/host.S | 5 +++++ 4 files changed, 44 insertions(+), 7 deletions(-)