From: Paolo Bonzini <pbonzini@redhat.com>
To: Ashish Kalra <ashish.kalra@amd.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com,
joro@8bytes.org, bp@suse.de, thomas.lendacky@amd.com,
x86@kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, srutherford@google.com,
brijesh.singh@amd.com, dovmurik@linux.vnet.ibm.com,
tobin@ibm.com, jejb@linux.ibm.com, frankeh@us.ibm.com
Subject: Re: [PATCH v2 2/9] KVM: X86: Introduce KVM_HC_PAGE_ENC_STATUS hypercall
Date: Sun, 6 Dec 2020 11:25:18 +0100 [thread overview]
Message-ID: <5813902a-f272-a6fe-b32c-c470cb18c1ff@redhat.com> (raw)
In-Reply-To: <20201202212232.GB14672@ashkalra_ubuntu_server>
On 02/12/20 22:22, Ashish Kalra wrote:
> Hello Dave,
>
> On Wed, Dec 02, 2020 at 04:54:20PM +0000, Dr. David Alan Gilbert wrote:
>> * Ashish Kalra (Ashish.Kalra@amd.com) wrote:
>>> From: Brijesh Singh <brijesh.singh@amd.com>
>>>
>>> This hypercall is used by the SEV guest to notify a change in the page
>>> encryption status to the hypervisor. The hypercall should be invoked
>>> only when the encryption attribute is changed from encrypted -> decrypted
>>> and vice versa. By default all guest pages are considered encrypted.
>>
>> Is it defined whether these are supposed to be called before or after
>> the the page type has been changed; is it change the type and then
>> notify or the other way around?
It doesn't matter. However, you have do it before writing to the page,
and the content of the page is unspecified between the hypercall and the
write to the page.
So you cannot for example encrypt a page in place (using the same PFN
but different settings of the C bit), you need to do:
hypercall(); /* mark enc_data as encrypted */
/*
* The contents of enc_data is now undefined as it can change
* across migration.
*/
memset(enc_data, unenc_data, PAGE_SIZE);
Paolo
next prev parent reply other threads:[~2020-12-06 10:26 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-01 0:45 [PATCH v2 0/9] Add AMD SEV page encryption bitmap support Ashish Kalra
2020-12-01 0:45 ` [PATCH v2 1/9] KVM: x86: Add AMD SEV specific Hypercall3 Ashish Kalra
2020-12-03 0:34 ` Sean Christopherson
2020-12-04 17:16 ` Brijesh Singh
2020-12-06 10:26 ` Paolo Bonzini
2020-12-07 20:41 ` Sean Christopherson
2020-12-08 3:09 ` Steve Rutherford
2020-12-08 4:16 ` Kalra, Ashish
2020-12-08 16:29 ` Brijesh Singh
2020-12-11 22:55 ` Ashish Kalra
2020-12-12 4:56 ` Ashish Kalra
2020-12-18 19:39 ` Dr. David Alan Gilbert
[not found] ` <E79E09A2-F314-4B59-B7AE-07B1D422DF2B@amd.com>
2020-12-18 19:56 ` Dr. David Alan Gilbert
2021-01-06 23:05 ` Ashish Kalra
2021-01-07 1:01 ` Steve Rutherford
2021-01-07 1:34 ` Ashish Kalra
2021-01-07 8:05 ` Ashish Kalra
2021-01-08 0:47 ` Ashish Kalra
2021-01-08 0:55 ` Steve Rutherford
2021-01-07 17:07 ` Ashish Kalra
2021-01-07 17:26 ` Sean Christopherson
2021-01-07 18:41 ` Ashish Kalra
2021-01-07 19:22 ` Sean Christopherson
2021-01-08 0:54 ` Steve Rutherford
2021-01-08 16:56 ` Sean Christopherson
2020-12-01 0:46 ` [PATCH v2 2/9] KVM: X86: Introduce KVM_HC_PAGE_ENC_STATUS hypercall Ashish Kalra
2020-12-02 16:54 ` Dr. David Alan Gilbert
2020-12-02 21:22 ` Ashish Kalra
2020-12-06 10:25 ` Paolo Bonzini [this message]
2020-12-01 0:47 ` [PATCH v2 3/9] KVM: x86: Introduce KVM_GET_PAGE_ENC_BITMAP ioctl Ashish Kalra
2020-12-06 11:02 ` Dov Murik
2020-12-07 22:00 ` Ashish Kalra
2020-12-01 0:47 ` [PATCH v2 4/9] mm: x86: Invoke hypercall when page encryption status is changed Ashish Kalra
2020-12-01 0:47 ` [PATCH v2 5/9] KVM: x86: Introduce KVM_SET_PAGE_ENC_BITMAP ioctl Ashish Kalra
2020-12-01 0:47 ` [PATCH v2 6/9] KVM: SVM: Add support for static allocation of unified Page Encryption Bitmap Ashish Kalra
2020-12-01 0:48 ` [PATCH v2 7/9] KVM: x86: Mark _bss_decrypted section variables as decrypted in page encryption bitmap Ashish Kalra
2020-12-01 0:48 ` [PATCH v2 8/9] KVM: x86: Add kexec support for SEV " Ashish Kalra
2020-12-01 0:48 ` [PATCH v2 9/9] KVM: SVM: Bypass DBG_DECRYPT API calls for unecrypted guest memory Ashish Kalra
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5813902a-f272-a6fe-b32c-c470cb18c1ff@redhat.com \
--to=pbonzini@redhat.com \
--cc=ashish.kalra@amd.com \
--cc=bp@suse.de \
--cc=brijesh.singh@amd.com \
--cc=dgilbert@redhat.com \
--cc=dovmurik@linux.vnet.ibm.com \
--cc=frankeh@us.ibm.com \
--cc=hpa@zytor.com \
--cc=jejb@linux.ibm.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=srutherford@google.com \
--cc=tglx@linutronix.de \
--cc=thomas.lendacky@amd.com \
--cc=tobin@ibm.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).