diff mbox

[25/33] KVM: PPC: Add bc instruction emulation

Message ID 1403472217-22263-26-git-send-email-agraf@suse.de (mailing list archive)
State New, archived
Headers show

Commit Message

Alexander Graf June 22, 2014, 9:23 p.m. UTC 
This patch adds emulation support for conditional branches.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 arch/powerpc/include/asm/ppc-opcode.h |  1 +
 arch/powerpc/kvm/emulate.c            | 51 +++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)
diff mbox

Patch

diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index 5160af9..e130156 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -116,6 +116,7 @@ 
 
 #define OP_CMPI 11
 #define OP_ADDIS 15
+#define OP_BC   16
 #define OP_ORI  24
 #define OP_ANDI 28
 #define OP_LWZ  32
diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c
index 7b8acb0..aeadc30 100644
--- a/arch/powerpc/kvm/emulate.c
+++ b/arch/powerpc/kvm/emulate.c
@@ -473,6 +473,54 @@  static int kvmppc_emulate_cmp(struct kvm_vcpu *vcpu, u64 value0, u64 value1,
 	return EMULATE_DONE;
 }
 
+int kvmppc_emulate_bc(struct kvm_vcpu *vcpu, u32 inst, bool is_32bit)
+{
+	u64 addr = (s64)(s16)get_d(inst);
+	int bo = get_rt(inst);
+	int bi = get_ra(inst);
+
+	/* If not absolute, PC gets added */
+	if (!(inst & 0x2))
+		addr += kvmppc_get_pc(vcpu);
+	if (is_32bit)
+		addr = (u32)addr;
+
+	/* LR gets set with LK=1 */
+	if (inst & 0x1)
+		kvmppc_set_lr(vcpu, kvmppc_get_pc(vcpu) + 4);
+
+	/* CTR handling */
+	if (!(bo & 0x4)) {
+		ulong ctr = kvmppc_get_ctr(vcpu);
+		ctr--;
+		if (is_32bit)
+			ctr = (u32)ctr;
+		kvmppc_set_ctr(vcpu, ctr);
+		if (((bo & 0x2) && (ctr != 0)) ||
+		   (!(bo & 0x2) && (ctr == 0))) {
+			/* Condition not fulfilled, go to next inst */
+			return EMULATE_DONE;
+		}
+	}
+
+	/* CR handling */
+	if (!(bo & 0x10)) {
+		uint32_t mask = 1 << (3 - (bi & 0x3));
+		u32 cr_part = kvmppc_get_cr(vcpu) >> (28 - (bi & ~0x3));
+		if (((bo & 0x8) && (cr_part != mask)) ||
+		   (!(bo & 0x8) && (cr_part == mask))) {
+			/* Condition not fulfilled, go to next inst */
+			return EMULATE_DONE;
+		}
+	}
+
+	/* Off we branch ... */
+	kvmppc_set_pc(vcpu, addr);
+
+	/* Indicate that we don't want to advance the PC */
+	return EMULATE_AGAIN;
+}
+
 /* Emulates privileged and non-privileged instructions */
 int kvmppc_emulate_any_instruction(struct kvm_vcpu *vcpu)
 {
@@ -536,6 +584,9 @@  int kvmppc_emulate_any_instruction(struct kvm_vcpu *vcpu)
 		kvmppc_emulate_cmp(vcpu, value, (s16)get_d(inst), true,
 				   get_rt(inst) >> 2, !(get_rt(inst) & 1));
 		break;
+	case OP_BC:
+		emulated = kvmppc_emulate_bc(vcpu, inst, is_32bit);
+		break;
 	case 31:
 		switch (get_xop(inst)) {
 		case OP_31_XOP_MFCR: