[PATCH v2 10/11] KVM: arm: implement lazy world switch for debug registers
Zhichao Huang
zhichao.huang at linaro.org
Sat May 30 21:27:11 PDT 2015
Implement switching of the debug registers. While the number
of registers is massive, CPUs usually don't implement them all
(A15 has 6 breakpoints and 4 watchpoints, which gives us a total
of 22 registers "only").
Also, we only save/restore them when DBGDSCR has debug enabled,
or when we've flagged the debug registers as dirty. It means that
most of the time, we only save/restore DBGDSCR.
Signed-off-by: Zhichao Huang <zhichao.huang at linaro.org>
---
arch/arm/kvm/interrupts.S | 16 +++
arch/arm/kvm/interrupts_head.S | 256 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 272 insertions(+)
diff --git a/arch/arm/kvm/interrupts.S b/arch/arm/kvm/interrupts.S
index 79caf79..d626275 100644
--- a/arch/arm/kvm/interrupts.S
+++ b/arch/arm/kvm/interrupts.S
@@ -116,6 +116,12 @@ ENTRY(__kvm_vcpu_run)
read_cp15_state store_to_vcpu = 0
write_cp15_state read_from_vcpu = 1
+ @ Store hardware CP14 state and load guest state
+ compute_debug_state 1f
+ bl __save_host_debug_regs
+ bl __restore_guest_debug_regs
+
+1:
@ If the host kernel has not been configured with VFPv3 support,
@ then it is safer if we deny guests from using it as well.
#ifdef CONFIG_VFPv3
@@ -201,6 +207,16 @@ after_vfp_restore:
mrc p15, 0, r2, c0, c0, 5
mcr p15, 4, r2, c0, c0, 5
+ @ Store guest CP14 state and restore host state
+ skip_debug_state 1f
+ bl __save_guest_debug_regs
+ bl __restore_host_debug_regs
+ /* Clear the dirty flag for the next run, as all the state has
+ * already been saved. Note that we nuke the whole 32bit word.
+ * If we ever add more flags, we'll have to be more careful...
+ */
+ clear_debug_dirty_bit
+1:
@ Store guest CP15 state and restore host state
read_cp15_state store_to_vcpu = 1
write_cp15_state read_from_vcpu = 0
diff --git a/arch/arm/kvm/interrupts_head.S b/arch/arm/kvm/interrupts_head.S
index 3a0128c..ed406be 100644
--- a/arch/arm/kvm/interrupts_head.S
+++ b/arch/arm/kvm/interrupts_head.S
@@ -7,6 +7,7 @@
#define VCPU_USR_SP (VCPU_USR_REG(13))
#define VCPU_USR_LR (VCPU_USR_REG(14))
#define CP15_OFFSET(_cp15_reg_idx) (VCPU_CP15 + (_cp15_reg_idx * 4))
+#define CP14_OFFSET(_cp14_reg_idx) (VCPU_CP14 + ((_cp14_reg_idx) * 4))
/*
* Many of these macros need to access the VCPU structure, which is always
@@ -99,6 +100,10 @@ vcpu .req r0 @ vcpu pointer always in r0
mrs r8, LR_fiq
mrs r9, SPSR_fiq
push {r2-r9}
+
+ /* DBGDSCR reg */
+ mrc p14, 0, r2, c0, c1, 0
+ push {r2}
.endm
.macro pop_host_regs_mode mode
@@ -113,6 +118,9 @@ vcpu .req r0 @ vcpu pointer always in r0
* Clobbers all registers, in all modes, except r0 and r1.
*/
.macro restore_host_regs
+ pop {r2}
+ mcr p14, 0, r2, c0, c2, 2
+
pop {r2-r9}
msr r8_fiq, r2
msr r9_fiq, r3
@@ -161,6 +169,9 @@ vcpu .req r0 @ vcpu pointer always in r0
* Clobbers *all* registers.
*/
.macro restore_guest_regs
+ ldr r2, [vcpu, #CP14_OFFSET(cp14_DBGDSCRext)]
+ mcr p14, 0, r2, c0, c2, 2
+
restore_guest_regs_mode svc, #VCPU_SVC_REGS
restore_guest_regs_mode abt, #VCPU_ABT_REGS
restore_guest_regs_mode und, #VCPU_UND_REGS
@@ -239,6 +250,10 @@ vcpu .req r0 @ vcpu pointer always in r0
save_guest_regs_mode abt, #VCPU_ABT_REGS
save_guest_regs_mode und, #VCPU_UND_REGS
save_guest_regs_mode irq, #VCPU_IRQ_REGS
+
+ /* DBGDSCR reg */
+ mrc p14, 0, r2, c0, c1, 0
+ str r2, [vcpu, #CP14_OFFSET(cp14_DBGDSCRext)]
.endm
/* Reads cp15 registers from hardware and stores them in memory
@@ -438,6 +453,231 @@ vcpu .req r0 @ vcpu pointer always in r0
str r5, [vcpu, #VCPU_DEBUG_FLAGS]
.endm
+/* Assume r11/r12 in used, clobbers r2-r10 */
+.macro cp14_read_and_push Op2 skip_num
+ cmp \skip_num, #8
+ // if (skip_num >= 8) then skip c8-c15 directly
+ bge 1f
+ adr r2, 9998f
+ add r2, r2, \skip_num, lsl #2
+ bx r2
+1:
+ adr r2, 9999f
+ sub r3, \skip_num, #8
+ add r2, r2, r3, lsl #2
+ bx r2
+9998:
+ mrc p14, 0, r10, c0, c15, \Op2
+ mrc p14, 0, r9, c0, c14, \Op2
+ mrc p14, 0, r8, c0, c13, \Op2
+ mrc p14, 0, r7, c0, c12, \Op2
+ mrc p14, 0, r6, c0, c11, \Op2
+ mrc p14, 0, r5, c0, c10, \Op2
+ mrc p14, 0, r4, c0, c9, \Op2
+ mrc p14, 0, r3, c0, c8, \Op2
+ push {r3-r10}
+9999:
+ mrc p14, 0, r10, c0, c7, \Op2
+ mrc p14, 0, r9, c0, c6, \Op2
+ mrc p14, 0, r8, c0, c5, \Op2
+ mrc p14, 0, r7, c0, c4, \Op2
+ mrc p14, 0, r6, c0, c3, \Op2
+ mrc p14, 0, r5, c0, c2, \Op2
+ mrc p14, 0, r4, c0, c1, \Op2
+ mrc p14, 0, r3, c0, c0, \Op2
+ push {r3-r10}
+.endm
+
+/* Assume r11/r12 in used, clobbers r2-r10 */
+.macro cp14_pop_and_write Op2 skip_num
+ cmp \skip_num, #8
+ // if (skip_num >= 8) then skip c8-c15 directly
+ bge 1f
+ adr r2, 9998f
+ add r2, r2, \skip_num, lsl #2
+ pop {r3-r10}
+ bx r2
+1:
+ adr r2, 9999f
+ sub r3, \skip_num, #8
+ add r2, r2, r3, lsl #2
+ pop {r3-r10}
+ bx r2
+
+9998:
+ mcr p14, 0, r10, c0, c15, \Op2
+ mcr p14, 0, r9, c0, c14, \Op2
+ mcr p14, 0, r8, c0, c13, \Op2
+ mcr p14, 0, r7, c0, c12, \Op2
+ mcr p14, 0, r6, c0, c11, \Op2
+ mcr p14, 0, r5, c0, c10, \Op2
+ mcr p14, 0, r4, c0, c9, \Op2
+ mcr p14, 0, r3, c0, c8, \Op2
+
+ pop {r3-r10}
+9999:
+ mcr p14, 0, r10, c0, c7, \Op2
+ mcr p14, 0, r9, c0, c6, \Op2
+ mcr p14, 0, r8, c0, c5, \Op2
+ mcr p14, 0, r7, c0, c4, \Op2
+ mcr p14, 0, r6, c0, c3, \Op2
+ mcr p14, 0, r5, c0, c2, \Op2
+ mcr p14, 0, r4, c0, c1, \Op2
+ mcr p14, 0, r3, c0, c0, \Op2
+.endm
+
+/* Assume r11/r12 in used, clobbers r2-r3 */
+.macro cp14_read_and_str Op2 cp14_reg0 skip_num
+ adr r3, 1f
+ add r3, r3, \skip_num, lsl #3
+ bx r3
+1:
+ mrc p14, 0, r2, c0, c15, \Op2
+ str r2, [vcpu, #CP14_OFFSET(\cp14_reg0+15)]
+ mrc p14, 0, r2, c0, c14, \Op2
+ str r2, [vcpu, #CP14_OFFSET(\cp14_reg0+14)]
+ mrc p14, 0, r2, c0, c13, \Op2
+ str r2, [vcpu, #CP14_OFFSET(\cp14_reg0+13)]
+ mrc p14, 0, r2, c0, c12, \Op2
+ str r2, [vcpu, #CP14_OFFSET(\cp14_reg0+12)]
+ mrc p14, 0, r2, c0, c11, \Op2
+ str r2, [vcpu, #CP14_OFFSET(\cp14_reg0+11)]
+ mrc p14, 0, r2, c0, c10, \Op2
+ str r2, [vcpu, #CP14_OFFSET(\cp14_reg0+10)]
+ mrc p14, 0, r2, c0, c9, \Op2
+ str r2, [vcpu, #CP14_OFFSET(\cp14_reg0+9)]
+ mrc p14, 0, r2, c0, c8, \Op2
+ str r2, [vcpu, #CP14_OFFSET(\cp14_reg0+8)]
+ mrc p14, 0, r2, c0, c7, \Op2
+ str r2, [vcpu, #CP14_OFFSET(\cp14_reg0+7)]
+ mrc p14, 0, r2, c0, c6, \Op2
+ str r2, [vcpu, #CP14_OFFSET(\cp14_reg0+6)]
+ mrc p14, 0, r2, c0, c5, \Op2
+ str r2, [vcpu, #CP14_OFFSET(\cp14_reg0+5)]
+ mrc p14, 0, r2, c0, c4, \Op2
+ str r2, [vcpu, #CP14_OFFSET(\cp14_reg0+4)]
+ mrc p14, 0, r2, c0, c3, \Op2
+ str r2, [vcpu, #CP14_OFFSET(\cp14_reg0+3)]
+ mrc p14, 0, r2, c0, c2, \Op2
+ str r2, [vcpu, #CP14_OFFSET(\cp14_reg0+2)]
+ mrc p14, 0, r2, c0, c1, \Op2
+ str r2, [vcpu, #CP14_OFFSET(\cp14_reg0+1)]
+ mrc p14, 0, r2, c0, c0, \Op2
+ str r2, [vcpu, #CP14_OFFSET(\cp14_reg0)]
+.endm
+
+/* Assume r11/r12 in used, clobbers r2-r3 */
+.macro cp14_ldr_and_write Op2 cp14_reg0 skip_num
+ adr r3, 1f
+ add r3, r3, \skip_num, lsl #3
+ bx r3
+1:
+ ldr r2, [vcpu, #CP14_OFFSET(\cp14_reg0+15)]
+ mcr p14, 0, r2, c0, c15, \Op2
+ ldr r2, [vcpu, #CP14_OFFSET(\cp14_reg0+14)]
+ mcr p14, 0, r2, c0, c14, \Op2
+ ldr r2, [vcpu, #CP14_OFFSET(\cp14_reg0+13)]
+ mcr p14, 0, r2, c0, c13, \Op2
+ ldr r2, [vcpu, #CP14_OFFSET(\cp14_reg0+12)]
+ mcr p14, 0, r2, c0, c12, \Op2
+ ldr r2, [vcpu, #CP14_OFFSET(\cp14_reg0+11)]
+ mcr p14, 0, r2, c0, c11, \Op2
+ ldr r2, [vcpu, #CP14_OFFSET(\cp14_reg0+10)]
+ mcr p14, 0, r2, c0, c10, \Op2
+ ldr r2, [vcpu, #CP14_OFFSET(\cp14_reg0+9)]
+ mcr p14, 0, r2, c0, c9, \Op2
+ ldr r2, [vcpu, #CP14_OFFSET(\cp14_reg0+8)]
+ mcr p14, 0, r2, c0, c8, \Op2
+ ldr r2, [vcpu, #CP14_OFFSET(\cp14_reg0+7)]
+ mcr p14, 0, r2, c0, c7, \Op2
+ ldr r2, [vcpu, #CP14_OFFSET(\cp14_reg0+6)]
+ mcr p14, 0, r2, c0, c6, \Op2
+ ldr r2, [vcpu, #CP14_OFFSET(\cp14_reg0+5)]
+ mcr p14, 0, r2, c0, c5, \Op2
+ ldr r2, [vcpu, #CP14_OFFSET(\cp14_reg0+4)]
+ mcr p14, 0, r2, c0, c4, \Op2
+ ldr r2, [vcpu, #CP14_OFFSET(\cp14_reg0+3)]
+ mcr p14, 0, r2, c0, c3, \Op2
+ ldr r2, [vcpu, #CP14_OFFSET(\cp14_reg0+2)]
+ mcr p14, 0, r2, c0, c2, \Op2
+ ldr r2, [vcpu, #CP14_OFFSET(\cp14_reg0+1)]
+ mcr p14, 0, r2, c0, c1, \Op2
+ ldr r2, [vcpu, #CP14_OFFSET(\cp14_reg0)]
+ mcr p14, 0, r2, c0, c0, \Op2
+.endm
+
+/* Get extract number of BRPs and WRPs. Saved in r11/r12 */
+.macro read_hw_dbg_num
+ mrc p14, 0, r2, c0, c0, 0
+ ubfx r11, r2, #24, #4
+ add r11, r11, #1 // Extract BRPs
+ ubfx r12, r2, #28, #4
+ add r12, r12, #1 // Extract WRPs
+ mov r2, #16
+ sub r11, r2, r11 // How many BPs to skip
+ sub r12, r2, r12 // How many WPs to skip
+.endm
+
+/* Reads cp14 registers from hardware.
+ * Writes cp14 registers in-order to the stack.
+ *
+ * Assumes vcpu pointer in vcpu reg
+ *
+ * Clobbers r2-r12
+ */
+.macro save_host_debug_regs
+ read_hw_dbg_num
+ cp14_read_and_push #4, r11 @ DBGBVR
+ cp14_read_and_push #5, r11 @ DBGBCR
+ cp14_read_and_push #6, r12 @ DBGWVR
+ cp14_read_and_push #7, r12 @ DBGWCR
+.endm
+
+/* Reads cp14 registers from hardware.
+ * Writes cp14 registers in-order to the VCPU struct pointed to by vcpup.
+ *
+ * Assumes vcpu pointer in vcpu reg
+ *
+ * Clobbers r2-r12
+ */
+.macro save_guest_debug_regs
+ read_hw_dbg_num
+ cp14_read_and_str #4, cp14_DBGBVR0, r11
+ cp14_read_and_str #5, cp14_DBGBCR0, r11
+ cp14_read_and_str #6, cp14_DBGWVR0, r12
+ cp14_read_and_str #7, cp14_DBGWCR0, r12
+.endm
+
+/* Reads cp14 registers in-order from the stack.
+ * Writes cp14 registers to hardware.
+ *
+ * Assumes vcpu pointer in vcpu reg
+ *
+ * Clobbers r2-r12
+ */
+.macro restore_host_debug_regs
+ read_hw_dbg_num
+ cp14_pop_and_write #4, r11 @ DBGBVR
+ cp14_pop_and_write #5, r11 @ DBGBCR
+ cp14_pop_and_write #6, r12 @ DBGWVR
+ cp14_pop_and_write #7, r12 @ DBGWCR
+.endm
+
+/* Reads cp14 registers in-order from the VCPU struct pointed to by vcpup
+ * Writes cp14 registers to hardware.
+ *
+ * Assumes vcpu pointer in vcpu reg
+ *
+ * Clobbers r2-r12
+ */
+.macro restore_guest_debug_regs
+ read_hw_dbg_num
+ cp14_ldr_and_write #4, cp14_DBGBVR0, r11
+ cp14_ldr_and_write #5, cp14_DBGBCR0, r11
+ cp14_ldr_and_write #6, cp14_DBGWVR0, r12
+ cp14_ldr_and_write #7, cp14_DBGWCR0, r12
+.endm
+
/*
* Save the VGIC CPU state into memory
*
@@ -673,3 +913,19 @@ ARM_BE8(rev r6, r6 )
.macro load_vcpu
mrc p15, 4, vcpu, c13, c0, 2 @ HTPIDR
.endm
+
+__save_host_debug_regs:
+ save_host_debug_regs
+ bx lr
+
+__save_guest_debug_regs:
+ save_guest_debug_regs
+ bx lr
+
+__restore_host_debug_regs:
+ restore_host_debug_regs
+ bx lr
+
+__restore_guest_debug_regs:
+ restore_guest_debug_regs
+ bx lr
--
1.7.12.4
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