[PATCH 07/37] KVM: arm64: Separate SError detection from VAXorcism

[Andrew Scull <ascull@google.com>]

When exiting a guest, just check whether there is an SError pending and
set the bit in the exit code. The fixup then initiates the ceremony
should it be required.

The separation allows for easier choices to be made as to whether the
demonic consultation should proceed.

Signed-off-by: Andrew Scull <ascull@google.com>
---
 arch/arm64/include/asm/kvm_hyp.h        |  2 ++
 arch/arm64/kvm/hyp/entry.S              | 27 +++++++++++++++++--------
 arch/arm64/kvm/hyp/hyp-entry.S          |  1 -
 arch/arm64/kvm/hyp/include/hyp/switch.h |  4 ++++
 4 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
index 07745d9c49fc..50a774812761 100644
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -91,6 +91,8 @@ void deactivate_traps_vhe_put(void);
 
 u64 __guest_enter(struct kvm_vcpu *vcpu, struct kvm_cpu_context *host_ctxt);
 
+void __vaxorcize_serror(void);
+
 void __noreturn hyp_panic(struct kvm_cpu_context *host_ctxt);
 #ifdef __KVM_NVHE_HYPERVISOR__
 void __noreturn __hyp_do_panic(unsigned long, ...);
diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S
index 6a641fcff4f7..dc4e3e7e7407 100644
--- a/arch/arm64/kvm/hyp/entry.S
+++ b/arch/arm64/kvm/hyp/entry.S
@@ -174,18 +174,31 @@ alternative_if ARM64_HAS_RAS_EXTN
 	mrs_s	x2, SYS_DISR_EL1
 	str	x2, [x1, #(VCPU_FAULT_DISR - VCPU_CONTEXT)]
 	cbz	x2, 1f
-	msr_s	SYS_DISR_EL1, xzr
 	orr	x0, x0, #(1<<ARM_EXIT_WITH_SERROR_BIT)
-1:	ret
+	nop
+1:
 alternative_else
 	dsb	sy		// Synchronize against in-flight ld/st
 	isb			// Prevent an early read of side-effect free ISR
 	mrs	x2, isr_el1
-	tbnz	x2, #8, 2f	// ISR_EL1.A
-	ret
-	nop
+	tbz	x2, #8, 2f	// ISR_EL1.A
+	orr	x0, x0, #(1<<ARM_EXIT_WITH_SERROR_BIT)
 2:
 alternative_endif
+
+	ret
+SYM_FUNC_END(__guest_enter)
+
+/*
+ * void __vaxorcize_serror(void);
+ */
+SYM_FUNC_START(__vaxorcize_serror)
+
+alternative_if ARM64_HAS_RAS_EXTN
+	msr_s	SYS_DISR_EL1, xzr
+	ret
+alternative_else_nop_endif
+
 	// We know we have a pending asynchronous abort, now is the
 	// time to flush it out. From your VAXorcist book, page 666:
 	// "Threaten me not, oh Evil one!  For I speak with
@@ -193,7 +206,6 @@ alternative_endif
 	mrs	x2, elr_el2
 	mrs	x3, esr_el2
 	mrs	x4, spsr_el2
-	mov	x5, x0
 
 	msr	daifclr, #4	// Unmask aborts
 
@@ -217,6 +229,5 @@ abort_guest_exit_end:
 	msr	elr_el2, x2
 	msr	esr_el2, x3
 	msr	spsr_el2, x4
-	orr	x0, x0, x5
 1:	ret
-SYM_FUNC_END(__guest_enter)
+SYM_FUNC_END(__vaxorcize_serror)
diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
index e727bee8e110..c441aabb8ab0 100644
--- a/arch/arm64/kvm/hyp/hyp-entry.S
+++ b/arch/arm64/kvm/hyp/hyp-entry.S
@@ -177,7 +177,6 @@ el2_error:
 	adr	x1, abort_guest_exit_end
 	ccmp	x0, x1, #4, ne
 	b.ne	__hyp_panic
-	mov	x0, #(1 << ARM_EXIT_WITH_SERROR_BIT)
 	eret
 	sb
 
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 0511af14dc81..14a774d1a35a 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -405,6 +405,10 @@ static inline bool __hyp_handle_ptrauth(struct kvm_vcpu *vcpu)
  */
 static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
 {
+	/* Flush guest SErrors. */
+	if (ARM_SERROR_PENDING(*exit_code))
+		__vaxorcize_serror();
+
 	if (ARM_EXCEPTION_CODE(*exit_code) != ARM_EXCEPTION_IRQ)
 		vcpu->arch.fault.esr_el2 = read_sysreg_el2(SYS_ESR);
 
-- 
2.27.0.389.gc38d7665816-goog

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