From 955d8dc3ee555e9320fabbeab0969f9cf7660f9d Mon Sep 17 00:00:00 2001 From: James Hogan Date: Tue, 14 Mar 2017 10:15:14 +0000 Subject: [PATCH] KVM: MIPS: Implement HYPCALL emulation MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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. No actual hypercalls are yet supported, but this still allows us to safely step over hypercalls and set an error code in the return value for forward compatibility. Non-zero HYPCALL codes are not handled. We also document the hypercall ABI which asm/kvm_para.h uses. Signed-off-by: James Hogan Acked-by: Ralf Baechle Cc: Paolo Bonzini Cc: "Radim Krčmář" Cc: Andreas Herrmann Cc: David Daney Cc: Jonathan Corbet 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 feaaa63..a890529 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 $2 (v0). + KVM Hypercalls Documentation =========================== The template for each hypercall is: diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h index 05e785f..0d308d4 100644 --- a/arch/mips/include/asm/kvm_host.h +++ b/arch/mips/include/asm/kvm_host.h @@ -229,6 +229,7 @@ enum emulation_result { EMULATE_WAIT, /* WAIT instruction */ EMULATE_PRIV_FAIL, EMULATE_EXCEPT, /* A guest exception has been generated */ + EMULATE_HYPERCALL, /* HYPCALL instruction */ }; #define mips3_paddr_to_tlbpfn(x) \ @@ -832,6 +833,12 @@ unsigned int kvm_mips_config3_wrmask(struct kvm_vcpu *vcpu); unsigned int kvm_mips_config4_wrmask(struct kvm_vcpu *vcpu); unsigned int kvm_mips_config5_wrmask(struct kvm_vcpu *vcpu); +/* Hypercalls (hypcall.c) */ + +enum emulation_result kvm_mips_emul_hypcall(struct kvm_vcpu *vcpu, + union mips_instruction inst); +int kvm_mips_handle_hypcall(struct kvm_vcpu *vcpu); + /* Dynamic binary translation */ extern int kvm_mips_trans_cache_index(union mips_instruction inst, u32 *opc, struct kvm_vcpu *vcpu); diff --git a/arch/mips/include/uapi/asm/inst.h b/arch/mips/include/uapi/asm/inst.h index 77429d1..b5e46ae 100644 --- a/arch/mips/include/uapi/asm/inst.h +++ b/arch/mips/include/uapi/asm/inst.h @@ -179,7 +179,7 @@ enum cop0_coi_func { tlbr_op = 0x01, tlbwi_op = 0x02, tlbwr_op = 0x06, tlbp_op = 0x08, rfe_op = 0x10, eret_op = 0x18, - wait_op = 0x20, + wait_op = 0x20, hypcall_op = 0x28 }; /* diff --git a/arch/mips/kvm/Makefile b/arch/mips/kvm/Makefile index 847429d..e56403c 100644 --- a/arch/mips/kvm/Makefile +++ b/arch/mips/kvm/Makefile @@ -10,6 +10,7 @@ common-objs-$(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 d40cfaa..637753e 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 0000000..8306343 --- /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 +#include +#include + +#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 b1fa53b..3a854bb 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(); } -- 2.7.4