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From: Paolo Bonzini <pbonzini@redhat.com>
To: Dave Hansen <dave.hansen@intel.com>,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: x86@kernel.org, linux-sgx@vger.kernel.org, jarkko@kernel.org,
	dave.hansen@linux.intel.com, yang.zhong@intel.com
Subject: Re: [PATCH 1/2] x86: sgx_vepc: extract sgx_vepc_remove_page
Date: Mon, 13 Sep 2021 17:14:08 +0200	[thread overview]
Message-ID: <34632ea9-42d3-fdfa-ae47-e208751ab090@redhat.com> (raw)
In-Reply-To: <06db5a41-3485-9141-10b5-56ca57ed1792@intel.com>

On 13/09/21 16:55, Dave Hansen wrote:
>> By "Windows startup" I mean even after guest reboot.  Because another
>> process could sneak in and steal your EPC pages between a close() and an
>> open(), I'd like to have a way to EREMOVE the pages while keeping them
>> assigned to the specific vEPC instance, i.e.*without*  going through
>> sgx_vepc_free_page().
> Oh, so you want fresh EPC state for the guest, but you're concerned that
> the previous guest might have left them in a bad state.  The current
> method of getting a new vepc instance (which guarantees fresh state) has
> some other downsides.
> 
> Can't another process steal pages via sgxd and reclaim at any time?

vEPC pages never call sgx_mark_page_reclaimable, don't they?

> What's the extra concern here about going through a close()/open()
> cycle?  Performance?

Apart from reclaiming, /dev/sgx_vepc might disappear between the first 
open() and subsequent ones.

Paolo


  reply	other threads:[~2021-09-13 15:15 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-13 13:11 [RFC/RFT PATCH 0/2] x86: sgx_vepc: implement ioctl to EREMOVE all pages Paolo Bonzini
2021-09-13 13:11 ` [PATCH 1/2] x86: sgx_vepc: extract sgx_vepc_remove_page Paolo Bonzini
2021-09-13 14:05   ` Dave Hansen
2021-09-13 14:24     ` Paolo Bonzini
2021-09-13 14:55       ` Dave Hansen
2021-09-13 15:14         ` Paolo Bonzini [this message]
2021-09-13 15:29           ` Dave Hansen
2021-09-13 18:35             ` Paolo Bonzini
2021-09-13 19:25               ` Dave Hansen
2021-09-13 21:16                 ` Jarkko Sakkinen
2021-09-13 21:15               ` Jarkko Sakkinen
2021-09-13 21:13           ` Jarkko Sakkinen
2021-09-14  5:36             ` Paolo Bonzini
2021-09-14 16:05               ` Jarkko Sakkinen
2021-09-13 21:12         ` Jarkko Sakkinen
2021-09-13 21:00       ` Jarkko Sakkinen
2021-09-13 20:33   ` Jarkko Sakkinen
2021-09-13 13:11 ` [PATCH 2/2] x86: sgx_vepc: implement SGX_IOC_VEPC_REMOVE ioctl Paolo Bonzini
2021-09-13 19:33   ` Dave Hansen
2021-09-13 21:11     ` Sean Christopherson
2021-09-13 22:43       ` Dave Hansen
2021-09-14 10:55   ` Kai Huang
2021-09-14  7:10 ` [RFC/RFT PATCH 0/2] x86: sgx_vepc: implement ioctl to EREMOVE all pages Yang Zhong
2021-09-14 10:19   ` Paolo Bonzini
2021-09-14 16:42     ` Jarkko Sakkinen
2021-09-14 17:07       ` Paolo Bonzini
2021-09-14 17:40         ` Jarkko Sakkinen
2021-09-14 17:44           ` Jarkko Sakkinen
2021-09-15  8:28     ` Yang Zhong
2021-09-20 12:53 [PATCH " Paolo Bonzini
2021-09-20 12:54 ` [PATCH 1/2] x86: sgx_vepc: extract sgx_vepc_remove_page Paolo Bonzini
2021-09-21 19:44   ` Jarkko Sakkinen
2021-09-21 19:46     ` Jarkko Sakkinen
2021-09-23 12:08     ` Paolo Bonzini
2021-09-23 20:33       ` Jarkko Sakkinen

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