Commit 3e1d8656 authored by Atish Patra's avatar Atish Patra Committed by Anup Patel
Browse files

RISC-V: KVM: Add SBI HSM extension in KVM 



SBI HSM extension allows OS to start/stop harts any time. It also allows
ordered booting of harts instead of random booting.

Implement SBI HSM exntesion and designate the vcpu 0 as the boot vcpu id.
All other non-zero non-booting vcpus should be brought up by the OS
implementing HSM extension. If the guest OS doesn't implement HSM
extension, only single vcpu will be available to OS.

Signed-off-by: default avatarAtish Patra <atish.patra@wdc.com>
Signed-off-by: default avatarAtish Patra <atishp@rivosinc.com>
Signed-off-by: default avatarAnup Patel <anup.patel@wdc.com>
parent 5f862df5

arch/riscv/include/asm/sbi.h

+1 −0
Original line number Diff line number Diff line
@@ -90,6 +90,7 @@ enum sbi_hsm_hart_status { 
#define SBI_ERR_INVALID_PARAM	-3

#define SBI_ERR_DENIED		-4

#define SBI_ERR_INVALID_ADDRESS	-5

#define SBI_ERR_ALREADY_AVAILABLE -6



extern unsigned long sbi_spec_version;

struct sbiret {

arch/riscv/kvm/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -22,4 +22,5 @@ kvm-y += vcpu_sbi.o 
kvm-$(CONFIG_RISCV_SBI_V01) += vcpu_sbi_v01.o

kvm-y += vcpu_sbi_base.o

kvm-y += vcpu_sbi_replace.o

kvm-y += vcpu_sbi_hsm.o

kvm-y += vcpu_timer.o

arch/riscv/kvm/vcpu.c

+23 −0
Original line number Diff line number Diff line
@@ -53,6 +53,17 @@ static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu) 
	struct kvm_vcpu_csr *reset_csr = &vcpu->arch.guest_reset_csr;

	struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;

	struct kvm_cpu_context *reset_cntx = &vcpu->arch.guest_reset_context;

	bool loaded;



	/**

	 * The preemption should be disabled here because it races with

	 * kvm_sched_out/kvm_sched_in(called from preempt notifiers) which

	 * also calls vcpu_load/put.

	 */

	get_cpu();

	loaded = (vcpu->cpu != -1);

	if (loaded)

		kvm_arch_vcpu_put(vcpu);



	memcpy(csr, reset_csr, sizeof(*csr));
@@ -64,6 +75,11 @@ static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu) 


	WRITE_ONCE(vcpu->arch.irqs_pending, 0);

	WRITE_ONCE(vcpu->arch.irqs_pending_mask, 0);



	/* Reset the guest CSRs for hotplug usecase */

	if (loaded)

		kvm_arch_vcpu_load(vcpu, smp_processor_id());

	put_cpu();

}



int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
@@ -101,6 +117,13 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu) 


void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)

{

	/**

	 * vcpu with id 0 is the designated boot cpu.

	 * Keep all vcpus with non-zero id in power-off state so that

	 * they can be brought up using SBI HSM extension.

	 */

	if (vcpu->vcpu_idx != 0)

		kvm_riscv_vcpu_power_off(vcpu);

}



void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)

arch/riscv/kvm/vcpu_sbi.c

+4 −0
Original line number Diff line number Diff line
@@ -25,6 +25,8 @@ static int kvm_linux_err_map_sbi(int err) 
		return SBI_ERR_INVALID_ADDRESS;

	case -EOPNOTSUPP:

		return SBI_ERR_NOT_SUPPORTED;

	case -EALREADY:

		return SBI_ERR_ALREADY_AVAILABLE;

	default:

		return SBI_ERR_FAILURE;

	};
@@ -43,6 +45,7 @@ extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_base; 
extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_time;

extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_ipi;

extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_rfence;

extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_hsm;



static const struct kvm_vcpu_sbi_extension *sbi_ext[] = {

	&vcpu_sbi_ext_v01,
@@ -50,6 +53,7 @@ static const struct kvm_vcpu_sbi_extension *sbi_ext[] = { 
	&vcpu_sbi_ext_time,

	&vcpu_sbi_ext_ipi,

	&vcpu_sbi_ext_rfence,

	&vcpu_sbi_ext_hsm,

};



void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu, struct kvm_run *run)

arch/riscv/kvm/vcpu_sbi_hsm.c

0 → 100644
+105 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * Copyright (c) 2021 Western Digital Corporation or its affiliates.

 *

 * Authors:

 *     Atish Patra <atish.patra@wdc.com>

 */



#include <linux/errno.h>

#include <linux/err.h>

#include <linux/kvm_host.h>

#include <asm/csr.h>

#include <asm/sbi.h>

#include <asm/kvm_vcpu_sbi.h>



static int kvm_sbi_hsm_vcpu_start(struct kvm_vcpu *vcpu)

{

	struct kvm_cpu_context *reset_cntx;

	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;

	struct kvm_vcpu *target_vcpu;

	unsigned long target_vcpuid = cp->a0;



	target_vcpu = kvm_get_vcpu_by_id(vcpu->kvm, target_vcpuid);

	if (!target_vcpu)

		return -EINVAL;

	if (!target_vcpu->arch.power_off)

		return -EALREADY;



	reset_cntx = &target_vcpu->arch.guest_reset_context;

	/* start address */

	reset_cntx->sepc = cp->a1;

	/* target vcpu id to start */

	reset_cntx->a0 = target_vcpuid;

	/* private data passed from kernel */

	reset_cntx->a1 = cp->a2;

	kvm_make_request(KVM_REQ_VCPU_RESET, target_vcpu);



	kvm_riscv_vcpu_power_on(target_vcpu);



	return 0;

}



static int kvm_sbi_hsm_vcpu_stop(struct kvm_vcpu *vcpu)

{

	if (vcpu->arch.power_off)

		return -EINVAL;



	kvm_riscv_vcpu_power_off(vcpu);



	return 0;

}



static int kvm_sbi_hsm_vcpu_get_status(struct kvm_vcpu *vcpu)

{

	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;

	unsigned long target_vcpuid = cp->a0;

	struct kvm_vcpu *target_vcpu;



	target_vcpu = kvm_get_vcpu_by_id(vcpu->kvm, target_vcpuid);

	if (!target_vcpu)

		return -EINVAL;

	if (!target_vcpu->arch.power_off)

		return SBI_HSM_HART_STATUS_STARTED;

	else

		return SBI_HSM_HART_STATUS_STOPPED;

}



static int kvm_sbi_ext_hsm_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,

				   unsigned long *out_val,

				   struct kvm_cpu_trap *utrap,

				   bool *exit)

{

	int ret = 0;

	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;

	struct kvm *kvm = vcpu->kvm;

	unsigned long funcid = cp->a6;



	switch (funcid) {

	case SBI_EXT_HSM_HART_START:

		mutex_lock(&kvm->lock);

		ret = kvm_sbi_hsm_vcpu_start(vcpu);

		mutex_unlock(&kvm->lock);

		break;

	case SBI_EXT_HSM_HART_STOP:

		ret = kvm_sbi_hsm_vcpu_stop(vcpu);

		break;

	case SBI_EXT_HSM_HART_STATUS:

		ret = kvm_sbi_hsm_vcpu_get_status(vcpu);

		if (ret >= 0) {

			*out_val = ret;

			ret = 0;

		}

		break;

	default:

		ret = -EOPNOTSUPP;

	}



	return ret;

}



const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_hsm = {

	.extid_start = SBI_EXT_HSM,

	.extid_end = SBI_EXT_HSM,

	.handler = kvm_sbi_ext_hsm_handler,

};