Avoid world-switching all the debug registers when neither the host
nor the guest has configured any [WB]points.
Signed-off-by: Zhichao Huang <zhichao.hu...@linaro.org>
---
arch/arm/kvm/interrupts_head.S | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
diff --git a/arch/arm/kvm/interrupts_head.S b/arch/arm/kvm/interrupts_head.S
index b9e7410..7ad0adf 100644
--- a/arch/arm/kvm/interrupts_head.S
+++ b/arch/arm/kvm/interrupts_head.S
@@ -332,6 +332,21 @@ vcpu .req r0 @ vcpu pointer always
in r0
sub r12, r2, r12 @ How many WPs to skip
.endm
+/* If VCPU_DEBUG_FLAGS is not set, it means that neither the host
+ * nor the guest has configured any [WB]points.
+ *
+ * We avoid world-switching all the debug registers in that case.
+ *
+ * Assume vcpu pointer in vcpu reg
+ *
+ * clobbers r2
+ */
+.macro skip_debug_state target
+ ldr r2, [vcpu, #VCPU_DEBUG_FLAGS]
+ cmp r2, #0
+ beq \target
+.endm
+
/* Reads cp14 registers from hardware.
* Writes cp14 registers in-order to the CP14 struct pointed to by r10
*
@@ -340,12 +355,14 @@ vcpu .req r0 @ vcpu pointer always
in r0
* Clobbers r2-r12
*/
.macro save_debug_state
+ skip_debug_state 9999f
+
read_hw_dbg_num
cp14_read_and_str r10, 4, cp14_DBGBVR0, r11
cp14_read_and_str r10, 5, cp14_DBGBCR0, r11
cp14_read_and_str r10, 6, cp14_DBGWVR0, r12
cp14_read_and_str r10, 7, cp14_DBGWCR0, r12
-
+9999:
/* DBGDSCR reg */
mrc p14, 0, r2, c0, c1, 0
str r2, [r10, #CP14_OFFSET(cp14_DBGDSCRext)]
@@ -359,12 +376,14 @@ vcpu .req r0 @ vcpu pointer always
in r0
* Clobbers r2-r12
*/
.macro restore_debug_state
+ skip_debug_state 9999f
+
read_hw_dbg_num
cp14_ldr_and_write r10, 4, cp14_DBGBVR0, r11
cp14_ldr_and_write r10, 5, cp14_DBGBCR0, r11
cp14_ldr_and_write r10, 6, cp14_DBGWVR0, r12
cp14_ldr_and_write r10, 7, cp14_DBGWCR0, r12
-
+9999:
/* DBGDSCR reg */
ldr r2, [r10, #CP14_OFFSET(cp14_DBGDSCRext)]
mcr p14, 0, r2, c0, c2, 2
--
1.7.12.4
--
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