diff mbox

[v2,08/36] KVM: arm64: Slightly improve debug save/restore functions

Message ID 20171207170630.592-9-christoffer.dall@linaro.org (mailing list archive)
State New, archived
Headers show

Commit Message

Christoffer Dall Dec. 7, 2017, 5:06 p.m. UTC 
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.

Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---

Notes:
    Changes since v1:
     - Change dot to comma in comment
     - Rename __debug_restore_spe to __debug_restore_spe_nvhe

 arch/arm64/kvm/hyp/debug-sr.c | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

Comments

Marc Zyngier Dec. 9, 2017, 7:37 p.m. UTC | #1 
On Thu, 07 Dec 2017 17:06:02 +0000,
Christoffer Dall wrote:
> 
> 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.
> 
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

	M.
diff mbox

Patch

diff --git a/arch/arm64/kvm/hyp/debug-sr.c b/arch/arm64/kvm/hyp/debug-sr.c
index 406829b6a43e..81b8ad44f9e0 100644
--- a/arch/arm64/kvm/hyp/debug-sr.c
+++ b/arch/arm64/kvm/hyp/debug-sr.c
@@ -65,11 +65,6 @@ 
 	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;
@@ -99,11 +94,7 @@  static void __hyp_text __debug_save_spe_nvhe(u64 *pmscr_el1)
 	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;
@@ -164,17 +155,24 @@  void __hyp_text __debug_cond_save_host_state(struct kvm_vcpu *vcpu)
 {
 	__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)