linux-kernel - Re: [PATCH v2 2/2] Drivers: hv: Introduce mshv

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Message-ID: <82cf1c07-026b-470e-b093-018dcfced5aa@oracle.com>
Date: Wed, 14 May 2025 02:04:10 +0530
From: ALOK TIWARI <alok.a.tiwari@...cle.com>
To: Naman Jain <namjain@...ux.microsoft.com>,
        "K . Y . Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>, Wei Liu <wei.liu@...nel.org>,
        Dexuan Cui <decui@...rosoft.com>
Cc: Roman Kisel <romank@...ux.microsoft.com>,
        Anirudh Rayabharam <anrayabh@...ux.microsoft.com>,
        Saurabh Sengar <ssengar@...ux.microsoft.com>,
        Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>,
        Nuno Das Neves <nunodasneves@...ux.microsoft.com>,
        linux-kernel@...r.kernel.org, linux-hyperv@...r.kernel.org
Subject: Re: [PATCH v2 2/2] Drivers: hv: Introduce mshv_vtl driver


> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2023, Microsoft Corporation.
> + *
> + * Author:
> + *   Roman Kisel <romank@...ux.microsoft.com>
> + *   Saurabh Sengar <ssengar@...ux.microsoft.com>
> + *   Naman Jain <namjain@...ux.microsoft.com>
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/miscdevice.h>
> +#include <linux/anon_inodes.h>
> +#include <linux/pfn_t.h>
> +#include <linux/cpuhotplug.h>
> +#include <linux/count_zeros.h>
> +#include <linux/eventfd.h>
> +#include <linux/poll.h>
> +#include <linux/file.h>
> +#include <linux/vmalloc.h>
> +#include <asm/debugreg.h>
> +#include <asm/mshyperv.h>
> +#include <trace/events/ipi.h>
> +#include <uapi/asm/mtrr.h>
> +#include <uapi/linux/mshv.h>
> +#include <hyperv/hvhdk.h>
> +
> +#include "../../kernel/fpu/legacy.h"
> +#include "mshv.h"
> +#include "mshv_vtl.h"
> +#include "hyperv_vmbus.h"
> +
> +MODULE_AUTHOR("Microsoft");
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Microsoft Hyper-V VTL Driver");
> +
> +#define MSHV_ENTRY_REASON_LOWER_VTL_CALL     0x1
> +#define MSHV_ENTRY_REASON_INTERRUPT          0x2
> +#define MSHV_ENTRY_REASON_INTERCEPT          0x3
> +
> +#define MAX_GUEST_MEM_SIZE	BIT_ULL(40)
> +#define MSHV_PG_OFF_CPU_MASK	0xFFFF
> +#define MSHV_REAL_OFF_SHIFT	16
> +#define MSHV_RUN_PAGE_OFFSET	0
> +#define MSHV_REG_PAGE_OFFSET	1
> +#define VTL2_VMBUS_SINT_INDEX	7
> +
> +static struct device *mem_dev;
> +
> +static struct tasklet_struct msg_dpc;
> +static wait_queue_head_t fd_wait_queue;
> +static bool has_message;
> +static struct eventfd_ctx *flag_eventfds[HV_EVENT_FLAGS_COUNT];
> +static DEFINE_MUTEX(flag_lock);
> +static bool __read_mostly mshv_has_reg_page;
> +
> +struct mshv_vtl_hvcall_fd {
> +	u64 allow_bitmap[2 * PAGE_SIZE];
> +	bool allow_map_intialized;

typo allow_map_intialized -> allow_map_initialized

> +	/*
> +	 * Used to protect hvcall setup in IOCTLs
> +	 */
> +	struct mutex init_mutex;
> +	struct miscdevice *dev;
> +};
> +
> +struct mshv_vtl_poll_file {
> +	struct file *file;
> +	wait_queue_entry_t wait;
> +	wait_queue_head_t *wqh;
> +	poll_table pt;
> +	int cpu;
> +};
> +
[clip]
> +
> +static int mshv_vtl_hvcall_setup(struct mshv_vtl_hvcall_fd *fd,
> +				 struct mshv_vtl_hvcall_setup __user *hvcall_setup_user)
> +{
> +	int ret = 0;
> +	struct mshv_vtl_hvcall_setup hvcall_setup;
> +
> +	mutex_lock(&fd->init_mutex);
> +
> +	if (fd->allow_map_intialized) {
> +		dev_err(fd->dev->this_device,
> +			"Hypercall allow map has already been set, pid %d\n",
> +			current->pid);
> +		ret = -EINVAL;
> +		goto exit;
> +	}
> +
> +	if (copy_from_user(&hvcall_setup, hvcall_setup_user,
> +			   sizeof(struct mshv_vtl_hvcall_setup))) {
> +		ret = -EFAULT;
> +		goto exit;
> +	}
> +	if (hvcall_setup.bitmap_size > ARRAY_SIZE(fd->allow_bitmap)) {
> +		ret = -EINVAL;
> +		goto exit;
> +	}

is this valid case if hvcall_setup.bitmap_size == 0 ?

> +	if (copy_from_user(&fd->allow_bitmap,
> +			   (void __user *)hvcall_setup.allow_bitmap_ptr,
> +			   hvcall_setup.bitmap_size)) {
> +		ret = -EFAULT;
> +		goto exit;
> +	}
> +
[clip]



Reviewed-by: Alok Tiwari <alok.a.tiwari@...cle.com>

Thanks,
Alok