[PATCH 0/4] KVM: MIPS: Hypercalls

[PATCH 0/4] KVM: MIPS: Hypercalls

[James Hogan]

This series implements some basic hypercalls for MIPS KVM, as used by
the MIPS paravirtual platform support in Linux and provided by Cavium's
VZ KVM implementation.

- Patch 1 hooks up trap & emulate to some minimal hypercall
  infrastructure without any hypercalls implemented yet. VZ support when
  it comes will also hook into the same infrastructure.

- Patches 2-3 implement GET_CLOCK_FREQ and EXIT_VM hypercalls.

- Patch 4 implements the console output hypercall by using
  KVM_EXIT_HYPERCALL (i.e. delegating the hypercall to userland). Its
  unclear if there is a more preferable approach to this, so comments
  particularly appreciated here.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-doc@vger.kernel.org

James Hogan (4):
  KVM: MIPS: Implement HYPCALL emulation
  KVM: MIPS: Implement GET_CLOCK_FREQ hypercall
  KVM: MIPS: Implement EXIT_VM hypercall
  KVM: MIPS: Implement console output hypercall

 Documentation/virtual/kvm/hypercalls.txt | 27 +++++++-
 arch/mips/include/asm/kvm_host.h         | 11 +++-
 arch/mips/include/uapi/asm/inst.h        |  2 +-
 arch/mips/kvm/Makefile                   |  1 +-
 arch/mips/kvm/emulate.c                  |  3 +-
 arch/mips/kvm/hypcall.c                  | 94 +++++++++++++++++++++++++-
 arch/mips/kvm/mips.c                     |  3 +-
 arch/mips/kvm/trap_emul.c                |  4 +-
 8 files changed, 144 insertions(+), 1 deletion(-)
 create mode 100644 arch/mips/kvm/hypcall.c

-- 
git-series 0.8.10

[PATCH 0/4] KVM: MIPS: Hypercalls

[James Hogan]

This series implements some basic hypercalls for MIPS KVM, as used by
the MIPS paravirtual platform support in Linux and provided by Cavium's
VZ KVM implementation.

- Patch 1 hooks up trap & emulate to some minimal hypercall
  infrastructure without any hypercalls implemented yet. VZ support when
  it comes will also hook into the same infrastructure.

- Patches 2-3 implement GET_CLOCK_FREQ and EXIT_VM hypercalls.

- Patch 4 implements the console output hypercall by using
  KVM_EXIT_HYPERCALL (i.e. delegating the hypercall to userland). Its
  unclear if there is a more preferable approach to this, so comments
  particularly appreciated here.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-doc@vger.kernel.org

James Hogan (4):
  KVM: MIPS: Implement HYPCALL emulation
  KVM: MIPS: Implement GET_CLOCK_FREQ hypercall
  KVM: MIPS: Implement EXIT_VM hypercall
  KVM: MIPS: Implement console output hypercall

 Documentation/virtual/kvm/hypercalls.txt | 27 +++++++-
 arch/mips/include/asm/kvm_host.h         | 11 +++-
 arch/mips/include/uapi/asm/inst.h        |  2 +-
 arch/mips/kvm/Makefile                   |  1 +-
 arch/mips/kvm/emulate.c                  |  3 +-
 arch/mips/kvm/hypcall.c                  | 94 +++++++++++++++++++++++++-
 arch/mips/kvm/mips.c                     |  3 +-
 arch/mips/kvm/trap_emul.c                |  4 +-
 8 files changed, 144 insertions(+), 1 deletion(-)
 create mode 100644 arch/mips/kvm/hypcall.c

-- 
git-series 0.8.10

[PATCH 1/4] KVM: MIPS: Implement HYPCALL emulation

[James Hogan]

Emulate the HYPCALL instruction added in the VZ ASE and used by the MIPS
paravirtualised guest support that is already merged. The new hypcall.c
handles arguments and the return value, and will handle the individual
hypercalls in upcoming commits.

Non-zero HYPCALL codes are not handled.

We also document the hypercall ABI which asm/kvm_para.h uses.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-doc@vger.kernel.org
---
 Documentation/virtual/kvm/hypercalls.txt |  5 ++-
 arch/mips/include/asm/kvm_host.h         |  7 +++-
 arch/mips/include/uapi/asm/inst.h        |  2 +-
 arch/mips/kvm/Makefile                   |  1 +-
 arch/mips/kvm/emulate.c                  |  3 +-
 arch/mips/kvm/hypcall.c                  | 53 +++++++++++++++++++++++++-
 arch/mips/kvm/trap_emul.c                |  4 ++-
 7 files changed, 74 insertions(+), 1 deletion(-)
 create mode 100644 arch/mips/kvm/hypcall.c

diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt
index c8d040e27046..8f36582ce2b7 100644
--- a/Documentation/virtual/kvm/hypercalls.txt
+++ b/Documentation/virtual/kvm/hypercalls.txt
@@ -28,6 +28,11 @@ S390:
   property inside the device tree's /hypervisor node.
   For more information refer to Documentation/virtual/kvm/ppc-pv.txt
 
+MIPS:
+  KVM hypercalls use the HYPCALL instruction with code 0 and the hypercall
+  number in $2 (v0). Up to four arguments may be placed in $4-$7 (a0-a3) and
+  the return value is placed in $2 (v0).
+
 KVM Hypercalls Documentation
 ===========================
 The template for each hypercall is:
diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index 05e785fc061d..0d308d4f2429 100644
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -229,6 +229,7 @@ enum emulation_result {
 	EMULATE_WAIT,		/* WAIT instruction */
 	EMULATE_PRIV_FAIL,
 	EMULATE_EXCEPT,		/* A guest exception has been generated */
+	EMULATE_HYPERCALL,	/* HYPCALL instruction */
 };
 
 #define mips3_paddr_to_tlbpfn(x) \
@@ -832,6 +833,12 @@ unsigned int kvm_mips_config3_wrmask(struct kvm_vcpu *vcpu);
 unsigned int kvm_mips_config4_wrmask(struct kvm_vcpu *vcpu);
 unsigned int kvm_mips_config5_wrmask(struct kvm_vcpu *vcpu);
 
+/* Hypercalls (hypcall.c) */
+
+enum emulation_result kvm_mips_emul_hypcall(struct kvm_vcpu *vcpu,
+					    union mips_instruction inst);
+int kvm_mips_handle_hypcall(struct kvm_vcpu *vcpu);
+
 /* Dynamic binary translation */
 extern int kvm_mips_trans_cache_index(union mips_instruction inst,
 				      u32 *opc, struct kvm_vcpu *vcpu);
diff --git a/arch/mips/include/uapi/asm/inst.h b/arch/mips/include/uapi/asm/inst.h
index 77429d1622b3..b5e46ae872d3 100644
--- a/arch/mips/include/uapi/asm/inst.h
+++ b/arch/mips/include/uapi/asm/inst.h
@@ -179,7 +179,7 @@ enum cop0_coi_func {
 	tlbr_op	      = 0x01, tlbwi_op	    = 0x02,
 	tlbwr_op      = 0x06, tlbp_op	    = 0x08,
 	rfe_op	      = 0x10, eret_op	    = 0x18,
-	wait_op       = 0x20,
+	wait_op       = 0x20, hypcall_op    = 0x28
 };
 
 /*
diff --git a/arch/mips/kvm/Makefile b/arch/mips/kvm/Makefile
index 847429de780d..e56403c8a3f5 100644
--- a/arch/mips/kvm/Makefile
+++ b/arch/mips/kvm/Makefile
@@ -10,6 +10,7 @@ common-objs-$(CONFIG_CPU_HAS_MSA) += msa.o
 kvm-objs := $(common-objs-y) mips.o emulate.o entry.o \
 	    interrupt.o stats.o commpage.o \
 	    dyntrans.o trap_emul.o fpu.o
+kvm-objs += hypcall.o
 kvm-objs += mmu.o
 
 obj-$(CONFIG_KVM)	+= kvm.o
diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c
index d40cfaad4529..637753ea0a00 100644
--- a/arch/mips/kvm/emulate.c
+++ b/arch/mips/kvm/emulate.c
@@ -1143,6 +1143,9 @@ enum emulation_result kvm_mips_emulate_CP0(union mips_instruction inst,
 		case wait_op:
 			er = kvm_mips_emul_wait(vcpu);
 			break;
+		case hypcall_op:
+			er = kvm_mips_emul_hypcall(vcpu, inst);
+			break;
 		}
 	} else {
 		rt = inst.c0r_format.rt;
diff --git a/arch/mips/kvm/hypcall.c b/arch/mips/kvm/hypcall.c
new file mode 100644
index 000000000000..83063435195f
--- /dev/null
+++ b/arch/mips/kvm/hypcall.c
@@ -0,0 +1,53 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * KVM/MIPS: Hypercall handling.
+ *
+ * Copyright (C) 2015  Imagination Technologies Ltd.
+ */
+
+#include <linux/kernel.h>
+#include <linux/kvm_host.h>
+#include <linux/kvm_para.h>
+
+#define MAX_HYPCALL_ARGS	4
+
+enum emulation_result kvm_mips_emul_hypcall(struct kvm_vcpu *vcpu,
+					    union mips_instruction inst)
+{
+	unsigned int code = (inst.co_format.code >> 5) & 0x3ff;
+
+	kvm_debug("[%#lx] HYPCALL %#03x\n", vcpu->arch.pc, code);
+
+	switch (code) {
+	case 0:
+		return EMULATE_HYPERCALL;
+	default:
+		return EMULATE_FAIL;
+	};
+}
+
+static int kvm_mips_hypercall(struct kvm_vcpu *vcpu, unsigned long num,
+			      const unsigned long *args, unsigned long *hret)
+{
+	/* Report unimplemented hypercall to guest */
+	*hret = -KVM_ENOSYS;
+	return RESUME_GUEST;
+}
+
+int kvm_mips_handle_hypcall(struct kvm_vcpu *vcpu)
+{
+	unsigned long num, args[MAX_HYPCALL_ARGS];
+
+	/* read hypcall number and arguments */
+	num = vcpu->arch.gprs[2];	/* v0 */
+	args[0] = vcpu->arch.gprs[4];	/* a0 */
+	args[1] = vcpu->arch.gprs[5];	/* a1 */
+	args[2] = vcpu->arch.gprs[6];	/* a2 */
+	args[3] = vcpu->arch.gprs[7];	/* a3 */
+
+	return kvm_mips_hypercall(vcpu, num,
+				  args, &vcpu->arch.gprs[2] /* v0 */);
+}
diff --git a/arch/mips/kvm/trap_emul.c b/arch/mips/kvm/trap_emul.c
index b1fa53b252ea..3a854bb9e606 100644
--- a/arch/mips/kvm/trap_emul.c
+++ b/arch/mips/kvm/trap_emul.c
@@ -82,6 +82,10 @@ static int kvm_trap_emul_handle_cop_unusable(struct kvm_vcpu *vcpu)
 		ret = RESUME_HOST;
 		break;
 
+	case EMULATE_HYPERCALL:
+		ret = kvm_mips_handle_hypcall(vcpu);
+		break;
+
 	default:
 		BUG();
 	}
-- 
git-series 0.8.10

[PATCH 1/4] KVM: MIPS: Implement HYPCALL emulation

[James Hogan]

Emulate the HYPCALL instruction added in the VZ ASE and used by the MIPS
paravirtualised guest support that is already merged. The new hypcall.c
handles arguments and the return value, and will handle the individual
hypercalls in upcoming commits.

Non-zero HYPCALL codes are not handled.

We also document the hypercall ABI which asm/kvm_para.h uses.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-doc@vger.kernel.org
---
 Documentation/virtual/kvm/hypercalls.txt |  5 ++-
 arch/mips/include/asm/kvm_host.h         |  7 +++-
 arch/mips/include/uapi/asm/inst.h        |  2 +-
 arch/mips/kvm/Makefile                   |  1 +-
 arch/mips/kvm/emulate.c                  |  3 +-
 arch/mips/kvm/hypcall.c                  | 53 +++++++++++++++++++++++++-
 arch/mips/kvm/trap_emul.c                |  4 ++-
 7 files changed, 74 insertions(+), 1 deletion(-)
 create mode 100644 arch/mips/kvm/hypcall.c

diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt
index c8d040e27046..8f36582ce2b7 100644
--- a/Documentation/virtual/kvm/hypercalls.txt
+++ b/Documentation/virtual/kvm/hypercalls.txt
@@ -28,6 +28,11 @@ S390:
   property inside the device tree's /hypervisor node.
   For more information refer to Documentation/virtual/kvm/ppc-pv.txt
 
+MIPS:
+  KVM hypercalls use the HYPCALL instruction with code 0 and the hypercall
+  number in $2 (v0). Up to four arguments may be placed in $4-$7 (a0-a3) and
+  the return value is placed in $2 (v0).
+
 KVM Hypercalls Documentation
 ===========================
 The template for each hypercall is:
diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index 05e785fc061d..0d308d4f2429 100644
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -229,6 +229,7 @@ enum emulation_result {
 	EMULATE_WAIT,		/* WAIT instruction */
 	EMULATE_PRIV_FAIL,
 	EMULATE_EXCEPT,		/* A guest exception has been generated */
+	EMULATE_HYPERCALL,	/* HYPCALL instruction */
 };
 
 #define mips3_paddr_to_tlbpfn(x) \
@@ -832,6 +833,12 @@ unsigned int kvm_mips_config3_wrmask(struct kvm_vcpu *vcpu);
 unsigned int kvm_mips_config4_wrmask(struct kvm_vcpu *vcpu);
 unsigned int kvm_mips_config5_wrmask(struct kvm_vcpu *vcpu);
 
+/* Hypercalls (hypcall.c) */
+
+enum emulation_result kvm_mips_emul_hypcall(struct kvm_vcpu *vcpu,
+					    union mips_instruction inst);
+int kvm_mips_handle_hypcall(struct kvm_vcpu *vcpu);
+
 /* Dynamic binary translation */
 extern int kvm_mips_trans_cache_index(union mips_instruction inst,
 				      u32 *opc, struct kvm_vcpu *vcpu);
diff --git a/arch/mips/include/uapi/asm/inst.h b/arch/mips/include/uapi/asm/inst.h
index 77429d1622b3..b5e46ae872d3 100644
--- a/arch/mips/include/uapi/asm/inst.h
+++ b/arch/mips/include/uapi/asm/inst.h
@@ -179,7 +179,7 @@ enum cop0_coi_func {
 	tlbr_op	      = 0x01, tlbwi_op	    = 0x02,
 	tlbwr_op      = 0x06, tlbp_op	    = 0x08,
 	rfe_op	      = 0x10, eret_op	    = 0x18,
-	wait_op       = 0x20,
+	wait_op       = 0x20, hypcall_op    = 0x28
 };
 
 /*
diff --git a/arch/mips/kvm/Makefile b/arch/mips/kvm/Makefile
index 847429de780d..e56403c8a3f5 100644
--- a/arch/mips/kvm/Makefile
+++ b/arch/mips/kvm/Makefile
@@ -10,6 +10,7 @@ common-objs-$(CONFIG_CPU_HAS_MSA) += msa.o
 kvm-objs := $(common-objs-y) mips.o emulate.o entry.o \
 	    interrupt.o stats.o commpage.o \
 	    dyntrans.o trap_emul.o fpu.o
+kvm-objs += hypcall.o
 kvm-objs += mmu.o
 
 obj-$(CONFIG_KVM)	+= kvm.o
diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c
index d40cfaad4529..637753ea0a00 100644
--- a/arch/mips/kvm/emulate.c
+++ b/arch/mips/kvm/emulate.c
@@ -1143,6 +1143,9 @@ enum emulation_result kvm_mips_emulate_CP0(union mips_instruction inst,
 		case wait_op:
 			er = kvm_mips_emul_wait(vcpu);
 			break;
+		case hypcall_op:
+			er = kvm_mips_emul_hypcall(vcpu, inst);
+			break;
 		}
 	} else {
 		rt = inst.c0r_format.rt;
diff --git a/arch/mips/kvm/hypcall.c b/arch/mips/kvm/hypcall.c
new file mode 100644
index 000000000000..83063435195f
--- /dev/null
+++ b/arch/mips/kvm/hypcall.c
@@ -0,0 +1,53 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * KVM/MIPS: Hypercall handling.
+ *
+ * Copyright (C) 2015  Imagination Technologies Ltd.
+ */
+
+#include <linux/kernel.h>
+#include <linux/kvm_host.h>
+#include <linux/kvm_para.h>
+
+#define MAX_HYPCALL_ARGS	4
+
+enum emulation_result kvm_mips_emul_hypcall(struct kvm_vcpu *vcpu,
+					    union mips_instruction inst)
+{
+	unsigned int code = (inst.co_format.code >> 5) & 0x3ff;
+
+	kvm_debug("[%#lx] HYPCALL %#03x\n", vcpu->arch.pc, code);
+
+	switch (code) {
+	case 0:
+		return EMULATE_HYPERCALL;
+	default:
+		return EMULATE_FAIL;
+	};
+}
+
+static int kvm_mips_hypercall(struct kvm_vcpu *vcpu, unsigned long num,
+			      const unsigned long *args, unsigned long *hret)
+{
+	/* Report unimplemented hypercall to guest */
+	*hret = -KVM_ENOSYS;
+	return RESUME_GUEST;
+}
+
+int kvm_mips_handle_hypcall(struct kvm_vcpu *vcpu)
+{
+	unsigned long num, args[MAX_HYPCALL_ARGS];
+
+	/* read hypcall number and arguments */
+	num = vcpu->arch.gprs[2];	/* v0 */
+	args[0] = vcpu->arch.gprs[4];	/* a0 */
+	args[1] = vcpu->arch.gprs[5];	/* a1 */
+	args[2] = vcpu->arch.gprs[6];	/* a2 */
+	args[3] = vcpu->arch.gprs[7];	/* a3 */
+
+	return kvm_mips_hypercall(vcpu, num,
+				  args, &vcpu->arch.gprs[2] /* v0 */);
+}
diff --git a/arch/mips/kvm/trap_emul.c b/arch/mips/kvm/trap_emul.c
index b1fa53b252ea..3a854bb9e606 100644
--- a/arch/mips/kvm/trap_emul.c
+++ b/arch/mips/kvm/trap_emul.c
@@ -82,6 +82,10 @@ static int kvm_trap_emul_handle_cop_unusable(struct kvm_vcpu *vcpu)
 		ret = RESUME_HOST;
 		break;
 
+	case EMULATE_HYPERCALL:
+		ret = kvm_mips_handle_hypcall(vcpu);
+		break;
+
 	default:
 		BUG();
 	}
-- 
git-series 0.8.10

[PATCH 2/4] KVM: MIPS: Implement GET_CLOCK_FREQ hypercall

[James Hogan]

Implement the MIPS GET_CLOCK_FREQ hypercall used by paravirtual guest
kernels. When the guest performs this hypercall, the value of count_hz
is returned, which is the current rate of the CP0_Count register.

We also document the hypercall along with the others as the
documentation was never added.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-doc@vger.kernel.org
---
 Documentation/virtual/kvm/hypercalls.txt |  6 ++++++
 arch/mips/kvm/hypcall.c                  | 18 +++++++++++++++---
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt
index 8f36582ce2b7..e9f1c9d3da98 100644
--- a/Documentation/virtual/kvm/hypercalls.txt
+++ b/Documentation/virtual/kvm/hypercalls.txt
@@ -86,3 +86,9 @@ the vcpu to sleep until occurrence of an appropriate event. Another vcpu of the
 same guest can wakeup the sleeping vcpu by issuing KVM_HC_KICK_CPU hypercall,
 specifying APIC ID (a1) of the vcpu to be woken up. An additional argument (a0)
 is used in the hypercall for future use.
+
+6. KVM_HC_MIPS_GET_CLOCK_FREQ
+------------------------
+Architecture: mips
+Status: active
+Purpose: Return the frequency of CP0_Count in HZ.
diff --git a/arch/mips/kvm/hypcall.c b/arch/mips/kvm/hypcall.c
index 83063435195f..7c74ec25f2b9 100644
--- a/arch/mips/kvm/hypcall.c
+++ b/arch/mips/kvm/hypcall.c
@@ -32,9 +32,21 @@ enum emulation_result kvm_mips_emul_hypcall(struct kvm_vcpu *vcpu,
 static int kvm_mips_hypercall(struct kvm_vcpu *vcpu, unsigned long num,
 			      const unsigned long *args, unsigned long *hret)
 {
-	/* Report unimplemented hypercall to guest */
-	*hret = -KVM_ENOSYS;
-	return RESUME_GUEST;
+	int ret = RESUME_GUEST;
+
+	switch (num) {
+	case KVM_HC_MIPS_GET_CLOCK_FREQ:
+		/* Return frequency of count/compare timer */
+		*hret = (s32)vcpu->arch.count_hz;
+		break;
+
+	default:
+		/* Report unimplemented hypercall to guest */
+		*hret = -KVM_ENOSYS;
+		break;
+	};
+
+	return ret;
 }
 
 int kvm_mips_handle_hypcall(struct kvm_vcpu *vcpu)
-- 
git-series 0.8.10

[PATCH 2/4] KVM: MIPS: Implement GET_CLOCK_FREQ hypercall

[James Hogan]

Implement the MIPS GET_CLOCK_FREQ hypercall used by paravirtual guest
kernels. When the guest performs this hypercall, the value of count_hz
is returned, which is the current rate of the CP0_Count register.

We also document the hypercall along with the others as the
documentation was never added.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-doc@vger.kernel.org
---
 Documentation/virtual/kvm/hypercalls.txt |  6 ++++++
 arch/mips/kvm/hypcall.c                  | 18 +++++++++++++++---
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt
index 8f36582ce2b7..e9f1c9d3da98 100644
--- a/Documentation/virtual/kvm/hypercalls.txt
+++ b/Documentation/virtual/kvm/hypercalls.txt
@@ -86,3 +86,9 @@ the vcpu to sleep until occurrence of an appropriate event. Another vcpu of the
 same guest can wakeup the sleeping vcpu by issuing KVM_HC_KICK_CPU hypercall,
 specifying APIC ID (a1) of the vcpu to be woken up. An additional argument (a0)
 is used in the hypercall for future use.
+
+6. KVM_HC_MIPS_GET_CLOCK_FREQ
+------------------------
+Architecture: mips
+Status: active
+Purpose: Return the frequency of CP0_Count in HZ.
diff --git a/arch/mips/kvm/hypcall.c b/arch/mips/kvm/hypcall.c
index 83063435195f..7c74ec25f2b9 100644
--- a/arch/mips/kvm/hypcall.c
+++ b/arch/mips/kvm/hypcall.c
@@ -32,9 +32,21 @@ enum emulation_result kvm_mips_emul_hypcall(struct kvm_vcpu *vcpu,
 static int kvm_mips_hypercall(struct kvm_vcpu *vcpu, unsigned long num,
 			      const unsigned long *args, unsigned long *hret)
 {
-	/* Report unimplemented hypercall to guest */
-	*hret = -KVM_ENOSYS;
-	return RESUME_GUEST;
+	int ret = RESUME_GUEST;
+
+	switch (num) {
+	case KVM_HC_MIPS_GET_CLOCK_FREQ:
+		/* Return frequency of count/compare timer */
+		*hret = (s32)vcpu->arch.count_hz;
+		break;
+
+	default:
+		/* Report unimplemented hypercall to guest */
+		*hret = -KVM_ENOSYS;
+		break;
+	};
+
+	return ret;
 }
 
 int kvm_mips_handle_hypcall(struct kvm_vcpu *vcpu)
-- 
git-series 0.8.10

[PATCH 3/4] KVM: MIPS: Implement EXIT_VM hypercall

[James Hogan]

Implement the MIPS EXIT_VM hypercall used by paravirtual guest kernels.
When the guest performs this hypercall, the request is passed to
userland in the form of a KVM_EXIT_SYSTEM_EVENT exit reason with system
event type KVM_SYSTEM_EVENT_SHUTDOWN.

We also document the hypercall along with the others as the
documentation was never added.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-doc@vger.kernel.org
---
 Documentation/virtual/kvm/hypercalls.txt |  6 ++++++
 arch/mips/kvm/hypcall.c                  |  9 +++++++++
 2 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt
index e9f1c9d3da98..f8108c84c46b 100644
--- a/Documentation/virtual/kvm/hypercalls.txt
+++ b/Documentation/virtual/kvm/hypercalls.txt
@@ -92,3 +92,9 @@ is used in the hypercall for future use.
 Architecture: mips
 Status: active
 Purpose: Return the frequency of CP0_Count in HZ.
+
+7. KVM_HC_MIPS_EXIT_VM
+------------------------
+Architecture: mips
+Status: active
+Purpose: Shut down the virtual machine.
diff --git a/arch/mips/kvm/hypcall.c b/arch/mips/kvm/hypcall.c
index 7c74ec25f2b9..c3345e5eec02 100644
--- a/arch/mips/kvm/hypcall.c
+++ b/arch/mips/kvm/hypcall.c
@@ -40,6 +40,15 @@ static int kvm_mips_hypercall(struct kvm_vcpu *vcpu, unsigned long num,
 		*hret = (s32)vcpu->arch.count_hz;
 		break;
 
+	case KVM_HC_MIPS_EXIT_VM:
+		/* Pass shutdown system event to userland */
+		memset(&vcpu->run->system_event, 0,
+		       sizeof(vcpu->run->system_event));
+		vcpu->run->system_event.type = KVM_SYSTEM_EVENT_SHUTDOWN;
+		vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
+		ret = RESUME_HOST;
+		break;
+
 	default:
 		/* Report unimplemented hypercall to guest */
 		*hret = -KVM_ENOSYS;
-- 
git-series 0.8.10

[PATCH 3/4] KVM: MIPS: Implement EXIT_VM hypercall

[James Hogan]

Implement the MIPS EXIT_VM hypercall used by paravirtual guest kernels.
When the guest performs this hypercall, the request is passed to
userland in the form of a KVM_EXIT_SYSTEM_EVENT exit reason with system
event type KVM_SYSTEM_EVENT_SHUTDOWN.

We also document the hypercall along with the others as the
documentation was never added.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-doc@vger.kernel.org
---
 Documentation/virtual/kvm/hypercalls.txt |  6 ++++++
 arch/mips/kvm/hypcall.c                  |  9 +++++++++
 2 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt
index e9f1c9d3da98..f8108c84c46b 100644
--- a/Documentation/virtual/kvm/hypercalls.txt
+++ b/Documentation/virtual/kvm/hypercalls.txt
@@ -92,3 +92,9 @@ is used in the hypercall for future use.
 Architecture: mips
 Status: active
 Purpose: Return the frequency of CP0_Count in HZ.
+
+7. KVM_HC_MIPS_EXIT_VM
+------------------------
+Architecture: mips
+Status: active
+Purpose: Shut down the virtual machine.
diff --git a/arch/mips/kvm/hypcall.c b/arch/mips/kvm/hypcall.c
index 7c74ec25f2b9..c3345e5eec02 100644
--- a/arch/mips/kvm/hypcall.c
+++ b/arch/mips/kvm/hypcall.c
@@ -40,6 +40,15 @@ static int kvm_mips_hypercall(struct kvm_vcpu *vcpu, unsigned long num,
 		*hret = (s32)vcpu->arch.count_hz;
 		break;
 
+	case KVM_HC_MIPS_EXIT_VM:
+		/* Pass shutdown system event to userland */
+		memset(&vcpu->run->system_event, 0,
+		       sizeof(vcpu->run->system_event));
+		vcpu->run->system_event.type = KVM_SYSTEM_EVENT_SHUTDOWN;
+		vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
+		ret = RESUME_HOST;
+		break;
+
 	default:
 		/* Report unimplemented hypercall to guest */
 		*hret = -KVM_ENOSYS;
-- 
git-series 0.8.10

[PATCH 4/4] KVM: MIPS: Implement console output hypercall

[James Hogan]

Implement console output hypercall by exiting back to userland with
KVM_EXIT_HYPERCALL, and setting the return value on next KVM_RUN.

We also document the hypercall along with the others as the
documentation was never added

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-doc@vger.kernel.org
---
Documentation/virtual/kvm/api.txt seems to suggest that
KVM_EXIT_HYPERCALL is obsolete. When it suggests using KVM_EXIT_MMIO,
does it simply mean the guest should use MMIO to some virtio device of
some sort rather than using hypercalls, or that the hypercall should
somehow be munged into the mmio exit information?
---
 Documentation/virtual/kvm/hypercalls.txt | 10 ++++++++++
 arch/mips/include/asm/kvm_host.h         |  4 ++++
 arch/mips/kvm/hypcall.c                  | 20 ++++++++++++++++++++
 arch/mips/kvm/mips.c                     |  3 +++
 4 files changed, 37 insertions(+), 0 deletions(-)

diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt
index f8108c84c46b..4e6e57026bfe 100644
--- a/Documentation/virtual/kvm/hypercalls.txt
+++ b/Documentation/virtual/kvm/hypercalls.txt
@@ -98,3 +98,13 @@ Purpose: Return the frequency of CP0_Count in HZ.
 Architecture: mips
 Status: active
 Purpose: Shut down the virtual machine.
+
+8. KVM_HC_MIPS_CONSOLE_OUTPUT
+------------------------
+Architecture: mips
+Status: active
+Purpose: Output a string to a console.
+Argument 1 contains the virtual terminal number to write to.
+Argument 2 contains a guest virtual address pointer to the string, which must
+be in an unmapped virtual memory segment (e.g. KSeg0, KSeg1 or XKPhys).
+Argument 3 contains the number of bytes to write.
diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index 0d308d4f2429..e0f1da0c35e9 100644
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -309,6 +309,9 @@ struct kvm_vcpu_arch {
 	/* GPR used as IO source/target */
 	u32 io_gpr;
 
+	/* Whether a hypercall needs completing */
+	int hypercall_needed;
+
 	struct hrtimer comparecount_timer;
 	/* Count timer control KVM register */
 	u32 count_ctl;
@@ -838,6 +841,7 @@ unsigned int kvm_mips_config5_wrmask(struct kvm_vcpu *vcpu);
 enum emulation_result kvm_mips_emul_hypcall(struct kvm_vcpu *vcpu,
 					    union mips_instruction inst);
 int kvm_mips_handle_hypcall(struct kvm_vcpu *vcpu);
+void kvm_mips_complete_hypercall(struct kvm_vcpu *vcpu, struct kvm_run *run);
 
 /* Dynamic binary translation */
 extern int kvm_mips_trans_cache_index(union mips_instruction inst,
diff --git a/arch/mips/kvm/hypcall.c b/arch/mips/kvm/hypcall.c
index c3345e5eec02..9cb8f37ca43a 100644
--- a/arch/mips/kvm/hypcall.c
+++ b/arch/mips/kvm/hypcall.c
@@ -33,6 +33,7 @@ static int kvm_mips_hypercall(struct kvm_vcpu *vcpu, unsigned long num,
 			      const unsigned long *args, unsigned long *hret)
 {
 	int ret = RESUME_GUEST;
+	int i;
 
 	switch (num) {
 	case KVM_HC_MIPS_GET_CLOCK_FREQ:
@@ -49,6 +50,19 @@ static int kvm_mips_hypercall(struct kvm_vcpu *vcpu, unsigned long num,
 		ret = RESUME_HOST;
 		break;
 
+	/* Hypercalls passed to userland to handle */
+	case KVM_HC_MIPS_CONSOLE_OUTPUT:
+		/* Pass to userland via KVM_EXIT_HYPERCALL */
+		memset(&vcpu->run->hypercall, 0, sizeof(vcpu->run->hypercall));
+		vcpu->run->hypercall.nr = num;
+		for (i = 0; i < MAX_HYPCALL_ARGS; ++i)
+			vcpu->run->hypercall.args[i] = args[i];
+		vcpu->run->hypercall.ret = -KVM_ENOSYS; /* default */
+		vcpu->run->exit_reason = KVM_EXIT_HYPERCALL;
+		vcpu->arch.hypercall_needed = 1;
+		ret = RESUME_HOST;
+		break;
+
 	default:
 		/* Report unimplemented hypercall to guest */
 		*hret = -KVM_ENOSYS;
@@ -72,3 +86,9 @@ int kvm_mips_handle_hypcall(struct kvm_vcpu *vcpu)
 	return kvm_mips_hypercall(vcpu, num,
 				  args, &vcpu->arch.gprs[2] /* v0 */);
 }
+
+void kvm_mips_complete_hypercall(struct kvm_vcpu *vcpu, struct kvm_run *run)
+{
+	vcpu->arch.gprs[2] = run->hypercall.ret;	/* v0 */
+	vcpu->arch.hypercall_needed = 0;
+}
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 31ee5ee0010b..1c23dc29db5d 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -409,6 +409,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 		vcpu->mmio_needed = 0;
 	}
 
+	if (vcpu->arch.hypercall_needed)
+		kvm_mips_complete_hypercall(vcpu, run);
+
 	lose_fpu(1);
 
 	local_irq_disable();
-- 
git-series 0.8.10

[PATCH 4/4] KVM: MIPS: Implement console output hypercall

[James Hogan]

Implement console output hypercall by exiting back to userland with
KVM_EXIT_HYPERCALL, and setting the return value on next KVM_RUN.

We also document the hypercall along with the others as the
documentation was never added

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-doc@vger.kernel.org
---
Documentation/virtual/kvm/api.txt seems to suggest that
KVM_EXIT_HYPERCALL is obsolete. When it suggests using KVM_EXIT_MMIO,
does it simply mean the guest should use MMIO to some virtio device of
some sort rather than using hypercalls, or that the hypercall should
somehow be munged into the mmio exit information?
---
 Documentation/virtual/kvm/hypercalls.txt | 10 ++++++++++
 arch/mips/include/asm/kvm_host.h         |  4 ++++
 arch/mips/kvm/hypcall.c                  | 20 ++++++++++++++++++++
 arch/mips/kvm/mips.c                     |  3 +++
 4 files changed, 37 insertions(+), 0 deletions(-)

diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt
index f8108c84c46b..4e6e57026bfe 100644
--- a/Documentation/virtual/kvm/hypercalls.txt
+++ b/Documentation/virtual/kvm/hypercalls.txt
@@ -98,3 +98,13 @@ Purpose: Return the frequency of CP0_Count in HZ.
 Architecture: mips
 Status: active
 Purpose: Shut down the virtual machine.
+
+8. KVM_HC_MIPS_CONSOLE_OUTPUT
+------------------------
+Architecture: mips
+Status: active
+Purpose: Output a string to a console.
+Argument 1 contains the virtual terminal number to write to.
+Argument 2 contains a guest virtual address pointer to the string, which must
+be in an unmapped virtual memory segment (e.g. KSeg0, KSeg1 or XKPhys).
+Argument 3 contains the number of bytes to write.
diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index 0d308d4f2429..e0f1da0c35e9 100644
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -309,6 +309,9 @@ struct kvm_vcpu_arch {
 	/* GPR used as IO source/target */
 	u32 io_gpr;
 
+	/* Whether a hypercall needs completing */
+	int hypercall_needed;
+
 	struct hrtimer comparecount_timer;
 	/* Count timer control KVM register */
 	u32 count_ctl;
@@ -838,6 +841,7 @@ unsigned int kvm_mips_config5_wrmask(struct kvm_vcpu *vcpu);
 enum emulation_result kvm_mips_emul_hypcall(struct kvm_vcpu *vcpu,
 					    union mips_instruction inst);
 int kvm_mips_handle_hypcall(struct kvm_vcpu *vcpu);
+void kvm_mips_complete_hypercall(struct kvm_vcpu *vcpu, struct kvm_run *run);
 
 /* Dynamic binary translation */
 extern int kvm_mips_trans_cache_index(union mips_instruction inst,
diff --git a/arch/mips/kvm/hypcall.c b/arch/mips/kvm/hypcall.c
index c3345e5eec02..9cb8f37ca43a 100644
--- a/arch/mips/kvm/hypcall.c
+++ b/arch/mips/kvm/hypcall.c
@@ -33,6 +33,7 @@ static int kvm_mips_hypercall(struct kvm_vcpu *vcpu, unsigned long num,
 			      const unsigned long *args, unsigned long *hret)
 {
 	int ret = RESUME_GUEST;
+	int i;
 
 	switch (num) {
 	case KVM_HC_MIPS_GET_CLOCK_FREQ:
@@ -49,6 +50,19 @@ static int kvm_mips_hypercall(struct kvm_vcpu *vcpu, unsigned long num,
 		ret = RESUME_HOST;
 		break;
 
+	/* Hypercalls passed to userland to handle */
+	case KVM_HC_MIPS_CONSOLE_OUTPUT:
+		/* Pass to userland via KVM_EXIT_HYPERCALL */
+		memset(&vcpu->run->hypercall, 0, sizeof(vcpu->run->hypercall));
+		vcpu->run->hypercall.nr = num;
+		for (i = 0; i < MAX_HYPCALL_ARGS; ++i)
+			vcpu->run->hypercall.args[i] = args[i];
+		vcpu->run->hypercall.ret = -KVM_ENOSYS; /* default */
+		vcpu->run->exit_reason = KVM_EXIT_HYPERCALL;
+		vcpu->arch.hypercall_needed = 1;
+		ret = RESUME_HOST;
+		break;
+
 	default:
 		/* Report unimplemented hypercall to guest */
 		*hret = -KVM_ENOSYS;
@@ -72,3 +86,9 @@ int kvm_mips_handle_hypcall(struct kvm_vcpu *vcpu)
 	return kvm_mips_hypercall(vcpu, num,
 				  args, &vcpu->arch.gprs[2] /* v0 */);
 }
+
+void kvm_mips_complete_hypercall(struct kvm_vcpu *vcpu, struct kvm_run *run)
+{
+	vcpu->arch.gprs[2] = run->hypercall.ret;	/* v0 */
+	vcpu->arch.hypercall_needed = 0;
+}
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 31ee5ee0010b..1c23dc29db5d 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -409,6 +409,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 		vcpu->mmio_needed = 0;
 	}
 
+	if (vcpu->arch.hypercall_needed)
+		kvm_mips_complete_hypercall(vcpu, run);
+
 	lose_fpu(1);
 
 	local_irq_disable();
-- 
git-series 0.8.10

Re: [PATCH 4/4] KVM: MIPS: Implement console output hypercall

[Paolo Bonzini]

On 06/02/2017 11:46, James Hogan wrote:
> Documentation/virtual/kvm/api.txt seems to suggest that
> KVM_EXIT_HYPERCALL is obsolete. When it suggests using KVM_EXIT_MMIO,
> does it simply mean the guest should use MMIO to some virtio device of
> some sort rather than using hypercalls, or that the hypercall should
> somehow be munged into the mmio exit information?

The former.

But there are cases when using hypercalls is unavoidable.  In that case
the trend is to use other exit reasons than KVM_EXIT_HYPERCALL, such as
KVM_EXIT_PAPR_HCALL in PowerPC.  Feel free to add KVM_EXIT_MIPS_CONOUT
or something like that.

How would you find the character device to write to in QEMU?

Paolo

Re: [PATCH 4/4] KVM: MIPS: Implement console output hypercall

[James Hogan]

[-- Attachment #1: Type: text/plain, Size: 1430 bytes --]

On Mon, Feb 06, 2017 at 02:25:59PM +0100, Paolo Bonzini wrote:
> 
> 
> On 06/02/2017 11:46, James Hogan wrote:
> > Documentation/virtual/kvm/api.txt seems to suggest that
> > KVM_EXIT_HYPERCALL is obsolete. When it suggests using KVM_EXIT_MMIO,
> > does it simply mean the guest should use MMIO to some virtio device of
> > some sort rather than using hypercalls, or that the hypercall should
> > somehow be munged into the mmio exit information?
> 
> The former.

Okay, thanks.

> 
> But there are cases when using hypercalls is unavoidable.  In that case
> the trend is to use other exit reasons than KVM_EXIT_HYPERCALL, such as
> KVM_EXIT_PAPR_HCALL in PowerPC.  Feel free to add KVM_EXIT_MIPS_CONOUT
> or something like that.

Okay, that sounds sensible. The existing mips_paravirt_defconfig does
contain CONFIG_VIRTIO_CONSOLE=y though, so I'm thinking we may be able
to get away without this hypercall and without old paravirt guest
kernels becoming unusable.

David/Andreas: would you agree, or do you feel strongly that this
hypercall API should be kept? (with a different KVM exit reason)

> 
> How would you find the character device to write to in QEMU?

I imagine it'd need a custom character device driver in QEMU so it could
be wired up to stdio/pty or whatever using QEMU arguments. I've only
tested it with a test case in my own MIPS KVM test suite so far though.

Cheers
James

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