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From: Dave Hansen <dave.hansen@intel.com>
To: "Huang, Kai" <kai.huang@intel.com>,
	"linux-sgx@vger.kernel.org" <linux-sgx@vger.kernel.org>,
	"Luck, Tony" <tony.luck@intel.com>,
	"Li, Zhiquan1" <zhiquan1.li@intel.com>,
	"jarkko@kernel.org" <jarkko@kernel.org>,
	"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>
Cc: "tglx@linutronix.de" <tglx@linutronix.de>,
	"Du, Fan" <fan.du@intel.com>, "Christopherson,,
	Sean" <seanjc@google.com>, "Zhang, Cathy" <cathy.zhang@intel.com>,
	"bp@suse.de" <bp@suse.de>
Subject: Re: [PATCH v9 3/3] x86/sgx: Fine grained SGX MCA behavior for virtualization
Date: Thu, 13 Oct 2022 15:28:50 -0700	[thread overview]
Message-ID: <4930999a-888f-88bc-a05c-86762504f059@intel.com> (raw)
In-Reply-To: <5ade54ce8e182307309426e1055dcc580c1dc5fc.camel@intel.com>

On 10/13/22 15:15, Huang, Kai wrote:
> On Thu, 2022-10-13 at 15:02 -0700, Hansen, Dave wrote:
>> Specifically, with this machine check SIGBUS implementation, one EPC
>> page can only have on host virtual address.  But, it's possible to
>> mmap() a single VEPC page in multiple processes at multiple host virtual
>> addresses.
>>
>> So, the implementation only allows one host virtual address.  But, we
>> can imagine a scenario where there are *TWO* valid virtual addresses
>> where the VEPC is mapped.
>>
>> What might happen in this case?  What's the fallout?
> 
> My understanding is there can be two #MC happening on two virtual addresses.
> 
> Each #MC will be injected to the VM which triggers that #MC to handle.

OK but which address with each of them see in siginfo->si_addr?  There's
only one ->vepc_vaddr.

It seems to me like this might result in the siginfo getting populated
with the ->si_addr from the *OTHER* process and *OTHER* virtual address.
 Basically, whoever allocates the page sets up *their* virtual address.
 Anyone else who gets a machine check on that page will see a virtual
address that has nothing to do with its virtual address space.

Is that problematic?

  reply	other threads:[~2022-10-13 22:29 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-20  6:39 [PATCH v9 0/3] x86/sgx: fine grained SGX MCA behavior Zhiquan Li
2022-09-20  6:39 ` [PATCH v9 1/3] x86/sgx: Rename the owner field of struct sgx_epc_page as encl_owner Zhiquan Li
2022-09-20  6:39 ` [PATCH v9 2/3] x86/sgx: Introduce union with vepc_vaddr field for virtualization case Zhiquan Li
2022-10-10 23:10   ` Dave Hansen
2022-10-11  5:49     ` Zhiquan Li
2022-10-11 13:57       ` Dave Hansen
2022-10-12  4:42         ` Zhiquan Li
2022-10-12 11:17           ` Huang, Kai
2022-09-20  6:39 ` [PATCH v9 3/3] x86/sgx: Fine grained SGX MCA behavior for virtualization Zhiquan Li
2022-10-10 23:20   ` Dave Hansen
2022-10-11  4:44     ` Zhiquan Li
2022-10-11 14:04   ` Dave Hansen
2022-10-12  5:09     ` Zhiquan Li
2022-10-12 11:01       ` Huang, Kai
2022-10-12 11:54         ` jarkko
2022-10-12 20:56           ` Huang, Kai
2022-10-13  2:05         ` Zhiquan Li
2022-10-12 14:36       ` Dave Hansen
2022-10-13 14:40         ` Zhiquan Li
2022-10-13 15:39           ` Dave Hansen
2022-10-14  5:42             ` Zhiquan Li
2022-10-14  5:41               ` Dave Hansen
2022-10-13 15:44           ` Dave Hansen
2022-10-13 21:49             ` Huang, Kai
2022-10-13 22:02               ` Dave Hansen
2022-10-13 22:15                 ` Huang, Kai
2022-10-13 22:28                   ` Dave Hansen [this message]
2022-10-13 23:40                     ` Huang, Kai
2022-10-13 23:57                       ` Dave Hansen
2022-10-14  0:19                         ` Huang, Kai
2022-10-19 10:59                           ` Huang, Kai
2022-10-23 20:39                             ` jarkko
2022-10-24  1:32                               ` Zhiquan Li
2022-11-01  0:46                                 ` jarkko
2022-11-02  1:38                                   ` Zhiquan Li
2022-11-07 11:36                                     ` jarkko
2022-11-07 12:19                                       ` Zhiquan Li
2022-11-04 10:17                                   ` Huang, Kai
2022-11-04 16:26                                     ` Sean Christopherson
2022-11-04 16:34                                       ` Dave Hansen
2022-11-07  8:55                                         ` Huang, Kai
2022-11-07  8:54                                       ` Huang, Kai
2022-10-24 22:23                               ` Huang, Kai
2022-11-01  0:53                                 ` jarkko
2022-09-29  8:05 ` [PATCH v9 0/3] x86/sgx: fine grained SGX MCA behavior Zhiquan Li
2022-10-08  2:29 ` Zhiquan Li

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