Re: [PATCH v2 3/3] x86/vmx: Disallow the use of inactivity states

From: Jan Beulich <jbeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: "Reima Ishii" <ishiir@g.ecc.u-tokyo.ac.jp>,
	"Roger Pau Monné" <roger.pau@citrix.com>, "Wei Liu" <wl@xen.org>,
	"Jun Nakajima" <jun.nakajima@intel.com>,
	"Kevin Tian" <kevin.tian@intel.com>,
	"Tamas K Lengyel" <tamas@tklengyel.com>,
	"Takahiro Shinagawa" <shina@ecc.u-tokyo.ac.jp>,
	"George Dunlap" <george.dunlap@citrix.com>,
	Xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH v2 3/3] x86/vmx: Disallow the use of inactivity states
Date: Fri, 12 Jan 2024 12:04:30 +0100	[thread overview]
Message-ID: <b25c0ff6-b2da-4e5b-b6b9-dca7843816d2@suse.com> (raw)
In-Reply-To: <8225cfd3-73d6-4a93-92b4-185399ab0ad3@citrix.com>

On 12.01.2024 11:43, Andrew Cooper wrote:
> On 12/01/2024 10:37 am, Jan Beulich wrote:
>> On 12.01.2024 00:13, Andrew Cooper wrote:
>>> --- a/xen/arch/x86/hvm/vmx/vmx.c
>>> +++ b/xen/arch/x86/hvm/vmx/vmx.c
>>> @@ -1551,7 +1551,10 @@ static void cf_check vmx_set_nonreg_state(struct vcpu *v,
>>>  {
>>>      vmx_vmcs_enter(v);
>>>  
>>> -    __vmwrite(GUEST_ACTIVITY_STATE, nrs->vmx.activity_state);
>>> +    if ( nrs->vmx.activity_state )
>>> +        domain_crash(v->domain, "Attempt to set activity_state %#lx\n",
>>> +                     nrs->vmx.activity_state);
>> Might be useful to log the offending vCPU here?
> 
> Already covered.  the innards of __domain_crash() does:
> 
>     else if ( d == current->domain )
>     {
>         printk("Domain %d (vcpu#%d) crashed on cpu#%d:\n",
>         ...

Except that afaict v != current here at all times (at least as far as
current use of the function goes).

Jan