From: Christoffer Dall <christoffer.dall@linaro.org>
Date: Tue, 10 Oct 2017 19:55:56 +0200
Subject: KVM: arm64: Slightly improve debug save/restore functions
Patch-mainline: v4.17-rc1
Git-commit: 5742d04912ebf7f2d5d169e4696bd1192ad32806
References: jsc#SLE-4084

The debug save/restore functions can be improved by using the has_vhe()
static key instead of the instruction alternative.  Using the static key
uses the same paradigm as we're going to use elsewhere, it makes the
code more readable, and it generates slightly better code (no
stack setups and function calls unless necessary).

We also use a static key on the restore path, because it will be
marginally faster than loading a value from memory.

Finally, we don't have to conditionally clear the debug dirty flag if
it's set, we can just clear it.

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Liang Yan <lyan@suse.com>
---
 arch/arm64/kvm/hyp/debug-sr.c |   26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

--- a/arch/arm64/kvm/hyp/debug-sr.c
+++ b/arch/arm64/kvm/hyp/debug-sr.c
@@ -66,11 +66,6 @@
 	default:	write_debug(ptr[0], reg, 0);			\
 	}
 
-static void __hyp_text __debug_save_spe_vhe(u64 *pmscr_el1)
-{
-	/* The vcpu can run. but it can't hide. */
-}
-
 static void __hyp_text __debug_save_spe_nvhe(u64 *pmscr_el1)
 {
 	u64 reg;
@@ -103,11 +98,7 @@ static void __hyp_text __debug_save_spe_
 	dsb(nsh);
 }
 
-static hyp_alternate_select(__debug_save_spe,
-			    __debug_save_spe_nvhe, __debug_save_spe_vhe,
-			    ARM64_HAS_VIRT_HOST_EXTN);
-
-static void __hyp_text __debug_restore_spe(u64 pmscr_el1)
+static void __hyp_text __debug_restore_spe_nvhe(u64 pmscr_el1)
 {
 	if (!pmscr_el1)
 		return;
@@ -168,17 +159,24 @@ void __hyp_text __debug_cond_save_host_s
 {
 	__debug_save_state(vcpu, &vcpu->arch.host_debug_state.regs,
 			   kern_hyp_va(vcpu->arch.host_cpu_context));
-	__debug_save_spe()(&vcpu->arch.host_debug_state.pmscr_el1);
+
+	/*
+	 * Non-VHE: Disable and flush SPE data generation
+	 * VHE: The vcpu can run, but it can't hide.
+	 */
+	if (!has_vhe())
+		__debug_save_spe_nvhe(&vcpu->arch.host_debug_state.pmscr_el1);
 }
 
 void __hyp_text __debug_cond_restore_host_state(struct kvm_vcpu *vcpu)
 {
-	__debug_restore_spe(vcpu->arch.host_debug_state.pmscr_el1);
+	if (!has_vhe())
+		__debug_restore_spe_nvhe(vcpu->arch.host_debug_state.pmscr_el1);
+
 	__debug_restore_state(vcpu, &vcpu->arch.host_debug_state.regs,
 			      kern_hyp_va(vcpu->arch.host_cpu_context));
 
-	if (vcpu->arch.debug_flags & KVM_ARM64_DEBUG_DIRTY)
-		vcpu->arch.debug_flags &= ~KVM_ARM64_DEBUG_DIRTY;
+	vcpu->arch.debug_flags &= ~KVM_ARM64_DEBUG_DIRTY;
 }
 
 u32 __hyp_text __kvm_get_mdcr_el2(void)