RISC-V: Add initial skeletal KVM support

This patch adds initial skeletal KVM RISC-V support which has: 1. A simple implementation of arch specific VM functions except kvm_vm_ioctl_get_dirty_log() which will implemeted in-future as part of stage2 page loging. 2. Stubs of required arch specific VCPU functions except kvm_arch_vcpu_ioctl_run() which is semi-complete and extended by subsequent patches. 3. Stubs for required arch specific stage2 MMU functions. Signed-off-by: Anup Patel <anup.patel@wdc.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Alexander Graf <graf@amazon.com> Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>

Author: avpatel

arch/riscv/Kconfig

@@ -562,4 +562,5 @@ source "kernel/power/Kconfig"
 
 endmenu
 
+source "arch/riscv/kvm/Kconfig"
 source "drivers/firmware/Kconfig"

arch/riscv/Makefile

@@ -100,6 +100,7 @@ endif
 head-y := arch/riscv/kernel/head.o
 
 core-$(CONFIG_RISCV_ERRATA_ALTERNATIVE) += arch/riscv/errata/
+core-$(CONFIG_KVM) += arch/riscv/kvm/
 
 libs-y += arch/riscv/lib/
 libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a

arch/riscv/include/asm/kvm_host.h

@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ * Anup Patel <anup.patel@wdc.com>
+ */
+
+#ifndef __RISCV_KVM_HOST_H__
+#define __RISCV_KVM_HOST_H__
+
+#include <linux/types.h>
+#include <linux/kvm.h>
+#include <linux/kvm_types.h>
+
+#ifdef CONFIG_64BIT
+#define KVM_MAX_VCPUS(1U << 16)
+#else
+#define KVM_MAX_VCPUS(1U << 9)
+#endif
+
+#define KVM_HALT_POLL_NS_DEFAULT500000
+
+#define KVM_VCPU_MAX_FEATURES0
+
+#define KVM_REQ_SLEEP \
+KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
+#define KVM_REQ_VCPU_RESETKVM_ARCH_REQ(1)
+
+struct kvm_vm_stat {
+struct kvm_vm_stat_generic generic;
+};
+
+struct kvm_vcpu_stat {
+struct kvm_vcpu_stat_generic generic;
+u64 ecall_exit_stat;
+u64 wfi_exit_stat;
+u64 mmio_exit_user;
+u64 mmio_exit_kernel;
+u64 exits;
+};
+
+struct kvm_arch_memory_slot {
+};
+
+struct kvm_arch {
+/* stage2 page table */
+pgd_t *pgd;
+phys_addr_t pgd_phys;
+};
+
+struct kvm_cpu_trap {
+unsigned long sepc;
+unsigned long scause;
+unsigned long stval;
+unsigned long htval;
+unsigned long htinst;
+};
+
+struct kvm_vcpu_arch {
+/* Don't run the VCPU (blocked) */
+bool pause;
+
+/* SRCU lock index for in-kernel run loop */
+int srcu_idx;
+};
+
+static inline void kvm_arch_hardware_unsetup(void) {}
+static inline void kvm_arch_sync_events(struct kvm *kvm) {}
+static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
+static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
+
+void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu);
+int kvm_riscv_stage2_alloc_pgd(struct kvm *kvm);
+void kvm_riscv_stage2_free_pgd(struct kvm *kvm);
+void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu);
+
+int kvm_riscv_vcpu_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run);
+int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
+struct kvm_cpu_trap *trap);
+
+static inline void __kvm_riscv_switch_to(struct kvm_vcpu_arch *vcpu_arch) {}
+
+#endif /* __RISCV_KVM_HOST_H__ */

arch/riscv/include/asm/kvm_types.h

@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_RISCV_KVM_TYPES_H
+#define _ASM_RISCV_KVM_TYPES_H
+
+#define KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE 40
+
+#endif /* _ASM_RISCV_KVM_TYPES_H */

arch/riscv/include/uapi/asm/kvm.h

@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ * Anup Patel <anup.patel@wdc.com>
+ */
+
+#ifndef __LINUX_KVM_RISCV_H
+#define __LINUX_KVM_RISCV_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+#include <asm/ptrace.h>
+
+#define __KVM_HAVE_READONLY_MEM
+
+#define KVM_COALESCED_MMIO_PAGE_OFFSET 1
+
+/* for KVM_GET_REGS and KVM_SET_REGS */
+struct kvm_regs {
+};
+
+/* for KVM_GET_FPU and KVM_SET_FPU */
+struct kvm_fpu {
+};
+
+/* KVM Debug exit structure */
+struct kvm_debug_exit_arch {
+};
+
+/* for KVM_SET_GUEST_DEBUG */
+struct kvm_guest_debug_arch {
+};
+
+/* definition of registers in kvm_run */
+struct kvm_sync_regs {
+};
+
+/* dummy definition */
+struct kvm_sregs {
+};
+
+#endif
+
+#endif /* __LINUX_KVM_RISCV_H */

arch/riscv/kvm/Kconfig

@@ -0,0 +1,33 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# KVM configuration
+#
+
+source "virt/kvm/Kconfig"
+
+menuconfig VIRTUALIZATION
+bool "Virtualization"
+help
+ Say Y here to get to see options for using your Linux host to run
+ other operating systems inside virtual machines (guests).
+ This option alone does not add any kernel code.
+
+ If you say N, all options in this submenu will be skipped and
+ disabled.
+
+if VIRTUALIZATION
+
+config KVM
+tristate "Kernel-based Virtual Machine (KVM) support (EXPERIMENTAL)"
+depends on RISCV_SBI && MMU
+select PREEMPT_NOTIFIERS
+select ANON_INODES
+select KVM_MMIO
+select HAVE_KVM_VCPU_ASYNC_IOCTL
+select SRCU
+help
+ Support hosting virtualized guest machines.
+
+ If unsure, say N.
+
+endif # VIRTUALIZATION

arch/riscv/kvm/Makefile

@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for RISC-V KVM support
+#
+
+ccflags-y += -I $(srctree)/$(src)
+
+KVM := ../../../virt/kvm
+
+obj-$(CONFIG_KVM) += kvm.o
+
+kvm-y += $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/binary_stats.o \
+ main.o vm.o mmu.o vcpu.o vcpu_exit.o

arch/riscv/kvm/main.c

@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ * Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/kvm_host.h>
+#include <asm/csr.h>
+#include <asm/hwcap.h>
+#include <asm/sbi.h>
+
+long kvm_arch_dev_ioctl(struct file *filp,
+unsigned int ioctl, unsigned long arg)
+{
+return -EINVAL;
+}
+
+int kvm_arch_check_processor_compat(void *opaque)
+{
+return 0;
+}
+
+int kvm_arch_hardware_setup(void *opaque)
+{
+return 0;
+}
+
+int kvm_arch_hardware_enable(void)
+{
+unsigned long hideleg, hedeleg;
+
+hedeleg = 0;
+hedeleg |= (1UL << EXC_INST_MISALIGNED);
+hedeleg |= (1UL << EXC_BREAKPOINT);
+hedeleg |= (1UL << EXC_SYSCALL);
+hedeleg |= (1UL << EXC_INST_PAGE_FAULT);
+hedeleg |= (1UL << EXC_LOAD_PAGE_FAULT);
+hedeleg |= (1UL << EXC_STORE_PAGE_FAULT);
+csr_write(CSR_HEDELEG, hedeleg);
+
+hideleg = 0;
+hideleg |= (1UL << IRQ_VS_SOFT);
+hideleg |= (1UL << IRQ_VS_TIMER);
+hideleg |= (1UL << IRQ_VS_EXT);
+csr_write(CSR_HIDELEG, hideleg);
+
+csr_write(CSR_HCOUNTEREN, -1UL);
+
+csr_write(CSR_HVIP, 0);
+
+return 0;
+}
+
+void kvm_arch_hardware_disable(void)
+{
+csr_write(CSR_HEDELEG, 0);
+csr_write(CSR_HIDELEG, 0);
+}
+
+int kvm_arch_init(void *opaque)
+{
+if (!riscv_isa_extension_available(NULL, h)) {
+kvm_info("hypervisor extension not available\n");
+return -ENODEV;
+}
+
+if (sbi_spec_is_0_1()) {
+kvm_info("require SBI v0.2 or higher\n");
+return -ENODEV;
+}
+
+if (sbi_probe_extension(SBI_EXT_RFENCE) <= 0) {
+kvm_info("require SBI RFENCE extension\n");
+return -ENODEV;
+}
+
+kvm_info("hypervisor extension available\n");
+
+return 0;
+}
+
+void kvm_arch_exit(void)
+{
+}
+
+static int riscv_kvm_init(void)
+{
+return kvm_init(NULL, sizeof(struct kvm_vcpu), 0, THIS_MODULE);
+}
+module_init(riscv_kvm_init);

arch/riscv/kvm/mmu.c

@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ * Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/hugetlb.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/vmalloc.h>
+#include <linux/kvm_host.h>
+#include <linux/sched/signal.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+
+void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
+{
+}
+
+void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free)
+{
+}
+
+void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen)
+{
+}
+
+void kvm_arch_flush_shadow_all(struct kvm *kvm)
+{
+/* TODO: */
+}
+
+void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
+ struct kvm_memory_slot *slot)
+{
+}
+
+void kvm_arch_commit_memory_region(struct kvm *kvm,
+const struct kvm_userspace_memory_region *mem,
+struct kvm_memory_slot *old,
+const struct kvm_memory_slot *new,
+enum kvm_mr_change change)
+{
+/* TODO: */
+}
+
+int kvm_arch_prepare_memory_region(struct kvm *kvm,
+struct kvm_memory_slot *memslot,
+const struct kvm_userspace_memory_region *mem,
+enum kvm_mr_change change)
+{
+/* TODO: */
+return 0;
+}
+
+void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu)
+{
+/* TODO: */
+}
+
+int kvm_riscv_stage2_alloc_pgd(struct kvm *kvm)
+{
+/* TODO: */
+return 0;
+}
+
+void kvm_riscv_stage2_free_pgd(struct kvm *kvm)
+{
+/* TODO: */
+}
+
+void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu)
+{
+/* TODO: */
+}