arch/riscv/kvm/vmid.c

Source file repositories/reference/linux-study-clean/arch/riscv/kvm/vmid.c

File Facts

System
Linux kernel
Corpus path
arch/riscv/kvm/vmid.c
Extension
.c
Size
3256 bytes
Lines
126
Domain
Architecture Layer
Bucket
arch/riscv
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

// 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/cpumask.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/smp.h>
#include <linux/kvm_host.h>
#include <asm/csr.h>
#include <asm/kvm_mmu.h>
#include <asm/kvm_tlb.h>
#include <asm/kvm_vmid.h>

static unsigned long vmid_version = 1;
static unsigned long vmid_next;
static unsigned long vmid_bits __ro_after_init;
static DEFINE_SPINLOCK(vmid_lock);

void __init kvm_riscv_gstage_vmid_detect(void)
{
	/* Figure-out number of VMID bits in HW */
	csr_write(CSR_HGATP, (kvm_riscv_gstage_mode(kvm_riscv_gstage_max_pgd_levels) <<
			      HGATP_MODE_SHIFT) | HGATP_VMID);
	vmid_bits = csr_read(CSR_HGATP);
	vmid_bits = (vmid_bits & HGATP_VMID) >> HGATP_VMID_SHIFT;
	vmid_bits = fls_long(vmid_bits);
	csr_write(CSR_HGATP, 0);

	/* We polluted local TLB so flush all guest TLB */
	kvm_riscv_local_hfence_gvma_all();

	/* We don't use VMID bits if they are not sufficient */
	if ((1UL << vmid_bits) < num_possible_cpus())
		vmid_bits = 0;
}

unsigned long kvm_riscv_gstage_vmid_bits(void)
{
	return vmid_bits;
}

int kvm_riscv_gstage_vmid_init(struct kvm *kvm)
{
	/* Mark the initial VMID and VMID version invalid */
	kvm->arch.vmid.vmid_version = 0;
	kvm->arch.vmid.vmid = 0;

	return 0;
}

bool kvm_riscv_gstage_vmid_ver_changed(struct kvm_vmid *vmid)
{
	if (!vmid_bits)
		return false;

	return unlikely(READ_ONCE(vmid->vmid_version) !=
			READ_ONCE(vmid_version));
}

static void __local_hfence_gvma_all(void *info)
{
	kvm_riscv_local_hfence_gvma_all();
}

void kvm_riscv_gstage_vmid_update(struct kvm_vcpu *vcpu)
{
	unsigned long i;
	struct kvm_vcpu *v;
	struct kvm_vmid *vmid = &vcpu->kvm->arch.vmid;

	if (!kvm_riscv_gstage_vmid_ver_changed(vmid))
		return;

	spin_lock(&vmid_lock);

	/*
	 * We need to re-check the vmid_version here to ensure that if
	 * another vcpu already allocated a valid vmid for this vm.
	 */
	if (!kvm_riscv_gstage_vmid_ver_changed(vmid)) {
		spin_unlock(&vmid_lock);
		return;
	}

Annotation

Implementation Notes