Patchwork [5/7] bookehv: Save and restore debug registers on guest entry and exit

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Submitter Bharat Bhushan
Date Feb. 28, 2013, 4:13 a.m.
Message ID <1362024796-4237-6-git-send-email-bharat.bhushan@freescale.com>
Download mbox | patch
Permalink /patch/223774/
State New
Headers show

Comments

Bharat Bhushan - Feb. 28, 2013, 4:13 a.m.
On Guest entry: if guest is wants to use the debug register then
save h/w debug register in host_dbg_reg and load the debug registers
with shadow_dbg_reg. Otherwise leave h/w debug registers as is.

On guest exit: If guest/user-space is using the debug resource then
restore the h/w debug register with host_dbg_reg. No need to save guest
debug register as shadow_dbg_reg is having required values. If guest is not
using the debug resources then no need to restore h/w registers.

Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
---
 arch/powerpc/kvm/bookehv_interrupts.S |  145 ++++++++++++++++++++++++++++++++-
 1 files changed, 141 insertions(+), 4 deletions(-)

Patch

diff --git a/arch/powerpc/kvm/bookehv_interrupts.S b/arch/powerpc/kvm/bookehv_interrupts.S
index e8ed7d6..0d830cc 100644
--- a/arch/powerpc/kvm/bookehv_interrupts.S
+++ b/arch/powerpc/kvm/bookehv_interrupts.S
@@ -62,6 +62,10 @@ 
 #define NEED_EMU		0x00000001 /* emulation -- save nv regs */
 #define NEED_DEAR		0x00000002 /* save faulting DEAR */
 #define NEED_ESR		0x00000004 /* save faulting ESR */
+#define NEED_DBSR		0x00000008 /* save DBSR */
+
+#define DBCR0_AC_BITS	(DBCR0_IAC1 | DBCR0_IAC2 | DBCR0_IAC3 | DBCR0_IAC4 | \
+			 DBCR0_DAC1R | DBCR0_DAC1W | DBCR0_DAC2R | DBCR0_DAC2W)
 
 /*
  * On entry:
@@ -201,6 +205,11 @@ 
 	PPC_STL	r9, VCPU_FAULT_DEAR(r4)
 	.endif
 
+	.if	\flags & NEED_DBSR
+	mfspr	r9, SPRN_DBSR
+	stw	r9, VCPU_DBSR(r4)
+	.endif
+
 	b	kvmppc_resume_host
 .endm
 
@@ -316,9 +325,9 @@  kvm_handler BOOKE_INTERRUPT_GUEST_DBELL, EX_PARAMS(GDBELL), \
 kvm_handler BOOKE_INTERRUPT_GUEST_DBELL_CRIT, EX_PARAMS(CRIT), \
 	SPRN_CSRR0, SPRN_CSRR1, 0
 kvm_handler BOOKE_INTERRUPT_DEBUG, EX_PARAMS(DBG), \
-	SPRN_DSRR0, SPRN_DSRR1, 0
+	SPRN_DSRR0, SPRN_DSRR1, NEED_DBSR
 kvm_handler BOOKE_INTERRUPT_DEBUG, EX_PARAMS(CRIT), \
-	SPRN_CSRR0, SPRN_CSRR1, 0
+	SPRN_CSRR0, SPRN_CSRR1, NEED_DBSR
 #else
 /*
  * For input register values, see arch/powerpc/include/asm/kvm_booke_hv_asm.h
@@ -411,9 +420,9 @@  kvm_handler BOOKE_INTERRUPT_GUEST_DBELL, SPRN_GSRR0, SPRN_GSRR1, 0
 kvm_lvl_handler BOOKE_INTERRUPT_GUEST_DBELL_CRIT, \
 	SPRN_SPRG_RSCRATCH_CRIT, SPRN_CSRR0, SPRN_CSRR1, 0
 kvm_lvl_handler BOOKE_INTERRUPT_DEBUG, \
-	SPRN_SPRG_RSCRATCH_CRIT, SPRN_CSRR0, SPRN_CSRR1, 0
+	SPRN_SPRG_RSCRATCH_CRIT, SPRN_CSRR0, SPRN_CSRR1, NEED_DBSR
 kvm_lvl_handler BOOKE_INTERRUPT_DEBUG, \
-	SPRN_SPRG_RSCRATCH_DBG, SPRN_DSRR0, SPRN_DSRR1, 0
+	SPRN_SPRG_RSCRATCH_DBG, SPRN_DSRR0, SPRN_DSRR1, NEED_DBSR
 #endif
 
 /* Registers:
@@ -423,6 +432,56 @@  kvm_lvl_handler BOOKE_INTERRUPT_DEBUG, \
  *  r14: KVM exit number
  */
 _GLOBAL(kvmppc_resume_host)
+	/*
+	 * If guest not used debug facility then hw debug registers
+	 * already have proper host values. If guest used debug
+	 * facility then restore host debug registers.
+	 * No Need to save guest debug registers as they are already intact
+	 * in guest/shadow registers.
+	 */
+	lwz	r9, VCPU_SHADOW_DBG+KVMPPC_DBG_DBCR0(r4)
+	rlwinm.	r8, r9, 0, ~DBCR0_IDM
+	beq	skip_load_host_debug
+	lwz	r3, VCPU_HOST_DBG+KVMPPC_DBG_DBCR0(r4)
+	andis.	r9, r9, DBCR0_AC_BITS@h
+	li	r9, 0
+	mtspr	SPRN_DBCR0, r9		/* disable all debug event */
+	beq	skip_load_hw_bkpts
+	lwz	r7, VCPU_HOST_DBG+KVMPPC_DBG_DBCR1(r4)
+	lwz	r8, VCPU_HOST_DBG+KVMPPC_DBG_DBCR2(r4)
+	lwz	r9, VCPU_HOST_DBG+KVMPPC_DBG_DBCR4(r4)
+	mtspr	SPRN_DBCR1, r7
+	PPC_LD(r6, VCPU_HOST_DBG+KVMPPC_DBG_IAC1, r4)
+	PPC_LD(r7, VCPU_HOST_DBG+KVMPPC_DBG_IAC2, r4)
+	mtspr	SPRN_DBCR2, r8
+	mtspr	SPRN_DBCR4, r9
+	mtspr	SPRN_IAC1, r6
+	mtspr	SPRN_IAC2, r7
+#if CONFIG_PPC_ADV_DEBUG_IACS > 2
+	PPC_LD(r7, VCPU_HOST_DBG+KVMPPC_DBG_IAC3, r4)
+	PPC_LD(r8, VCPU_HOST_DBG+KVMPPC_DBG_IAC4, r4)
+	mtspr	SPRN_IAC3, r7
+	mtspr	SPRN_IAC4, r8
+#endif
+	PPC_LD(r8, VCPU_HOST_DBG+KVMPPC_DBG_DAC1, r4)
+	PPC_LD(r9, VCPU_HOST_DBG+KVMPPC_DBG_DAC2, r4)
+	mtspr	SPRN_DAC1, r8
+	mtspr	SPRN_DAC2, r9
+skip_load_hw_bkpts:
+	isync
+	/* Clear h/w DBSR */
+	mfspr	r8, SPRN_DBSR
+	mtspr	SPRN_DBSR, r8
+	isync
+	/* Clear EPCR.DUVD and set host DBCR0 */
+	mfspr	r8, SPRN_EPCR
+	rlwinm	r8, r8, 0, ~SPRN_EPCR_DUVD
+	mtspr	SPRN_EPCR, r8
+	isync
+	mtspr	SPRN_DBCR0, r3
+	isync
+skip_load_host_debug:
+
 	/* Save remaining volatile guest register state to vcpu. */
 	mfspr	r3, SPRN_VRSAVE
 	PPC_STL	r0, VCPU_GPR(R0)(r4)
@@ -662,6 +721,84 @@  lightweight_exit:
 	mtspr	SPRN_SPRG6W, r7
 	mtspr	SPRN_SPRG7W, r8
 
+	mfmsr	r7
+	rlwinm	r7, r7, 0, ~MSR_DE
+	mtmsr	r7
+	/*
+	 * Load hw debug registers with guest(shadow) debug registers
+	 * if guest is using the debug facility and also set EPCR.DUVD
+	 * to not allow debug events in HV mode. Do not change the
+	 * debug registers if guest is not using the debug facility.
+	 */
+	lwz	r6, VCPU_SHADOW_DBG+KVMPPC_DBG_DBCR0(r4)
+	rlwinm.	r7, r6, 0, ~DBCR0_IDM
+	beq	skip_load_guest_debug
+	/* Save host DBCR0 */
+	mfspr	r8, SPRN_DBCR0
+	stw	r8, VCPU_HOST_DBG+KVMPPC_DBG_DBCR0(r4)
+	/*
+	 * Save host DBCR1/2, IACx and DACx and load guest DBCR1/2,
+	 * IACx and DACx if guest using hw breakpoint/watchpoints.
+	 */
+	andis.	r3, r6, DBCR0_AC_BITS@h
+	beq	skip_hw_bkpts
+	mfspr	r7, SPRN_DBCR1
+	stw	r7, VCPU_HOST_DBG+KVMPPC_DBG_DBCR1(r4)
+	mfspr	r8, SPRN_DBCR2
+	stw	r8, VCPU_HOST_DBG+KVMPPC_DBG_DBCR2(r4)
+	mfspr	r7, SPRN_DBCR4
+	stw	r7, VCPU_HOST_DBG+KVMPPC_DBG_DBCR4(r4)
+	mfspr	r8, SPRN_IAC1
+	PPC_STD(r8, VCPU_HOST_DBG+KVMPPC_DBG_IAC1, r4)
+	mfspr	r7, SPRN_IAC2
+	PPC_STD(r7, VCPU_HOST_DBG+KVMPPC_DBG_IAC2, r4)
+#if CONFIG_PPC_ADV_DEBUG_IACS > 2
+	mfspr	r8, SPRN_IAC3
+	PPC_STD(r8, VCPU_HOST_DBG+KVMPPC_DBG_IAC3, r4)
+	mfspr	r7, SPRN_IAC4
+	PPC_STD(r7, VCPU_HOST_DBG+KVMPPC_DBG_IAC4, r4)
+#endif
+	mfspr	r8, SPRN_DAC1
+	PPC_STD(r8, VCPU_HOST_DBG+KVMPPC_DBG_DAC1, r4)
+	mfspr	r7, SPRN_DAC2
+	PPC_STD(r7, VCPU_HOST_DBG+KVMPPC_DBG_DAC2, r4)
+	li	r8, 0
+	mtspr	SPRN_DBCR0, r8		/* disable all debug event */
+	lwz	r7, VCPU_SHADOW_DBG+KVMPPC_DBG_DBCR1(r4)
+	lwz	r8, VCPU_SHADOW_DBG+KVMPPC_DBG_DBCR2(r4)
+	lwz	r9, VCPU_SHADOW_DBG+KVMPPC_DBG_DBCR4(r4)
+	mtspr	SPRN_DBCR1, r7
+	PPC_LD(r7, VCPU_SHADOW_DBG+KVMPPC_DBG_IAC1, r4)
+	PPC_LD(r3, VCPU_SHADOW_DBG+KVMPPC_DBG_IAC2, r4)
+	mtspr	SPRN_DBCR2, r8
+	mtspr	SPRN_DBCR4, r9
+	mtspr	SPRN_IAC1, r7
+	mtspr	SPRN_IAC2, r3
+#if CONFIG_PPC_ADV_DEBUG_IACS > 2
+	PPC_LD(r7, VCPU_SHADOW_DBG+KVMPPC_DBG_IAC3, r4)
+	PPC_LD(r8, VCPU_SHADOW_DBG+KVMPPC_DBG_IAC4, r4)
+	mtspr	SPRN_IAC3, r7
+	mtspr	SPRN_IAC4, r8
+#endif
+	PPC_LD(r7, VCPU_SHADOW_DBG+KVMPPC_DBG_DAC1, r4)
+	PPC_LD(r8, VCPU_SHADOW_DBG+KVMPPC_DBG_DAC2, r4)
+	mtspr	SPRN_DAC1, r7
+	mtspr	SPRN_DAC2, r8
+skip_hw_bkpts:
+	/* Set EPCR.DUVD and guest DBCR0 */
+	mfspr	r7, SPRN_EPCR
+	oris	r7, r7, SPRN_EPCR_DUVD@h
+	mtspr	SPRN_EPCR, r7
+	isync
+	/* Clear if any deferred debug event */
+	mfspr	r8, SPRN_DBSR
+	mtspr	SPRN_DBSR, r8
+	isync
+	/* Restore guest DBCR */
+	mtspr	SPRN_DBCR0, r6
+	isync
+skip_load_guest_debug:
+
 	/* Load some guest volatiles. */
 	PPC_LL	r3, VCPU_LR(r4)
 	PPC_LL	r5, VCPU_XER(r4)