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Date:   Mon, 11 Jan 2021 11:59:46 +0800
From:   Shuo A Liu <shuo.a.liu@intel.com>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org,
        "H . Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Yu Wang <yu1.wang@intel.com>,
        Reinette Chatre <reinette.chatre@intel.com>,
        Zhi Wang <zhi.a.wang@intel.com>,
        Zhenyu Wang <zhenyuw@linux.intel.com>
Subject: Re: [PATCH v7 07/18] virt: acrn: Introduce an ioctl to set vCPU
 registers state
Message-ID: <20210111035946.GD22447@shuo-intel.sh.intel.com>
References: <20210106075055.47226-1-shuo.a.liu@intel.com>
 <20210106075055.47226-8-shuo.a.liu@intel.com>
 <X/h7QoSqRw2Anfvo@kroah.com>
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In-Reply-To: <X/h7QoSqRw2Anfvo@kroah.com>
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On Fri  8.Jan'21 at 16:33:22 +0100, Greg Kroah-Hartman wrote:
>On Wed, Jan 06, 2021 at 03:50:44PM +0800, shuo.a.liu@intel.com wrote:
>> From: Shuo Liu <shuo.a.liu@intel.com>
>>
>> A virtual CPU of User VM has different context due to the different
>> registers state. ACRN userspace needs to set the virtual CPU
>> registers state (e.g. giving a initial registers state to a virtual
>> BSP of a User VM).
>>
>> HSM provides an ioctl ACRN_IOCTL_SET_VCPU_REGS to do the virtual CPU
>> registers state setting. The ioctl passes the registers state from ACRN
>> userspace to the hypervisor directly.
>>
>> Signed-off-by: Shuo Liu <shuo.a.liu@intel.com>
>> Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
>> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
>> Cc: Zhi Wang <zhi.a.wang@intel.com>
>> Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
>> Cc: Yu Wang <yu1.wang@intel.com>
>> Cc: Reinette Chatre <reinette.chatre@intel.com>
>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> ---
>>  drivers/virt/acrn/hsm.c       | 21 ++++++++++-
>>  drivers/virt/acrn/hypercall.h | 13 +++++++
>>  include/uapi/linux/acrn.h     | 69 +++++++++++++++++++++++++++++++++++
>>  3 files changed, 102 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/virt/acrn/hsm.c b/drivers/virt/acrn/hsm.c
>> index 5fd933471683..2d04ebaa43f8 100644
>> --- a/drivers/virt/acrn/hsm.c
>> +++ b/drivers/virt/acrn/hsm.c
>> @@ -9,6 +9,7 @@
>>   *	Yakui Zhao <yakui.zhao@intel.com>
>>   */
>>
>> +#include <linux/io.h>
>>  #include <linux/mm.h>
>>  #include <linux/module.h>
>>  #include <linux/slab.h>
>> @@ -46,7 +47,8 @@ static long acrn_dev_ioctl(struct file *filp, unsigned int cmd,
>>  {
>>  	struct acrn_vm *vm = filp->private_data;
>>  	struct acrn_vm_creation *vm_param;
>> -	int ret = 0;
>> +	struct acrn_vcpu_regs *cpu_regs;
>> +	int i, ret = 0;
>>
>>  	if (vm->vmid == ACRN_INVALID_VMID && cmd != ACRN_IOCTL_CREATE_VM) {
>>  		dev_dbg(acrn_dev.this_device,
>> @@ -100,6 +102,23 @@ static long acrn_dev_ioctl(struct file *filp, unsigned int cmd,
>>  	case ACRN_IOCTL_DESTROY_VM:
>>  		ret = acrn_vm_destroy(vm);
>>  		break;
>> +	case ACRN_IOCTL_SET_VCPU_REGS:
>> +		cpu_regs = memdup_user((void __user *)ioctl_param,
>> +				       sizeof(struct acrn_vcpu_regs));
>> +		if (IS_ERR(cpu_regs))
>> +			return PTR_ERR(cpu_regs);
>> +
>> +		for (i = 0; i < ARRAY_SIZE(cpu_regs->reserved); i++)
>> +			if (cpu_regs->reserved[i])
>> +				return -EINVAL;
>> +
>> +		ret = hcall_set_vcpu_regs(vm->vmid, virt_to_phys(cpu_regs));
>> +		if (ret < 0)
>> +			dev_dbg(acrn_dev.this_device,
>> +				"Failed to set regs state of VM%u!\n",
>> +				vm->vmid);
>> +		kfree(cpu_regs);
>> +		break;
>>  	default:
>>  		dev_dbg(acrn_dev.this_device, "Unknown IOCTL 0x%x!\n", cmd);
>>  		ret = -ENOTTY;
>> diff --git a/drivers/virt/acrn/hypercall.h b/drivers/virt/acrn/hypercall.h
>> index 426b66cadb1f..f29cfae08862 100644
>> --- a/drivers/virt/acrn/hypercall.h
>> +++ b/drivers/virt/acrn/hypercall.h
>> @@ -19,6 +19,7 @@
>>  #define HC_START_VM			_HC_ID(HC_ID, HC_ID_VM_BASE + 0x02)
>>  #define HC_PAUSE_VM			_HC_ID(HC_ID, HC_ID_VM_BASE + 0x03)
>>  #define HC_RESET_VM			_HC_ID(HC_ID, HC_ID_VM_BASE + 0x05)
>> +#define HC_SET_VCPU_REGS		_HC_ID(HC_ID, HC_ID_VM_BASE + 0x06)
>>
>>  /**
>>   * hcall_create_vm() - Create a User VM
>> @@ -75,4 +76,16 @@ static inline long hcall_reset_vm(u64 vmid)
>>  	return acrn_hypercall1(HC_RESET_VM, vmid);
>>  }
>>
>> +/**
>> + * hcall_set_vcpu_regs() - Set up registers of virtual CPU of a User VM
>> + * @vmid:	User VM ID
>> + * @regs_state:	Service VM GPA of registers state
>> + *
>> + * Return: 0 on success, <0 on failure
>> + */
>> +static inline long hcall_set_vcpu_regs(u64 vmid, u64 regs_state)
>> +{
>> +	return acrn_hypercall2(HC_SET_VCPU_REGS, vmid, regs_state);
>> +}
>> +
>>  #endif /* __ACRN_HSM_HYPERCALL_H */
>> diff --git a/include/uapi/linux/acrn.h b/include/uapi/linux/acrn.h
>> index e1608b8a50a2..d5d66b93586e 100644
>> --- a/include/uapi/linux/acrn.h
>> +++ b/include/uapi/linux/acrn.h
>> @@ -35,6 +35,73 @@ struct acrn_vm_creation {
>>  	__u64	cpu_affinity;
>>  };
>>
>> +struct acrn_gp_regs {
>> +	__le64	rax;
>> +	__le64	rcx;
>> +	__le64	rdx;
>> +	__le64	rbx;
>> +	__le64	rsp;
>> +	__le64	rbp;
>> +	__le64	rsi;
>> +	__le64	rdi;
>> +	__le64	r8;
>> +	__le64	r9;
>> +	__le64	r10;
>> +	__le64	r11;
>> +	__le64	r12;
>> +	__le64	r13;
>> +	__le64	r14;
>> +	__le64	r15;
>> +};
>> +
>> +struct acrn_descriptor_ptr {
>> +	__le16	limit;
>> +	__le64	base;
>> +	__le16	reserved[3];
>> +} __attribute__ ((__packed__));
>> +
>> +struct acrn_regs {
>> +	struct acrn_gp_regs		gprs;
>> +	struct acrn_descriptor_ptr	gdt;
>> +	struct acrn_descriptor_ptr	idt;
>> +
>> +	__le64				rip;
>> +	__le64				cs_base;
>> +	__le64				cr0;
>> +	__le64				cr4;
>> +	__le64				cr3;
>> +	__le64				ia32_efer;
>> +	__le64				rflags;
>> +	__le64				reserved_64[4];
>> +
>> +	__le32				cs_ar;
>> +	__le32				cs_limit;
>> +	__le32				reserved_32[3];
>> +
>> +	__le16				cs_sel;
>> +	__le16				ss_sel;
>> +	__le16				ds_sel;
>> +	__le16				es_sel;
>> +	__le16				fs_sel;
>> +	__le16				gs_sel;
>> +	__le16				ldt_sel;
>> +	__le16				tr_sel;
>> +};
>
>No documentation of what these variables are anywhere?

I will add the documentation to explain them in this file.

>
>What about the reserved slots, what must they be set to?

Will document they shoud be zero and check them.

Thanks
shuo