From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: WeiLiu <wl@xen.org>,
Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
xen-devel <xen-devel@lists.xenproject.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Brian Woods <brian.woods@amd.com>,
Roger Pau Monne <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH] x86/svm: Fix svm_vmcb_dump() when used in current context
Date: Mon, 17 Jun 2019 14:59:19 +0100 [thread overview]
Message-ID: <905e57ed-4f26-f446-e04e-9f680bdedbb7@citrix.com> (raw)
In-Reply-To: <5D079BB50200007800238D2B@prv1-mh.provo.novell.com>
On 17/06/2019 14:55, Jan Beulich wrote:
>>>> On 17.06.19 at 14:54, <andrew.cooper3@citrix.com> wrote:
>> VMExit doesn't switch all state. The FS/GS/TS/LDTR/GSBASE segment
>> information, and SYSCALL/SYSENTER MSRs may still be cached in hardware, rather
>> than up-to-date in the VMCB.
>>
>> Export svm_sync_vmcb() via svmdebug.h so svm_vmcb_dump() can use it, and bring
>> the VMCB into sync in current context.
>>
>> As a minor optimisation, switch svm_sync_vmcb() to use svm_vm{load,save}_pa(),
>> as svm->vmcb_pa is always in correct, and this avoids a redundant __pa()
> Is the "in" here a leftover from some earlier, different wording?
Yes. It can be dropped.
>
>> translation behind the scenes.
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Reviewed-by: Jan Beulich <jbeulich@suse.com>
>
> Only as a remark: This removes the last use of svm_vmload(), but
> perhaps it and svm_vmsave() would better be dropped together,
> once the one remaining use of the latter has also disappeared
> (assuming that's doable).
I noticed and tried to do just that, but removing the final svm_vmsave()
isn't trivial. It is confined to the nested virt code, but I think it
is calling virt_to_maddr() on a domheap mapping, which needs adjusting
not to explode on a system with more than 5T of RAM.
Its in my todo list, but I don't have time to address that right now.
~Andrew
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next prev parent reply other threads:[~2019-06-17 13:59 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-17 12:54 [Xen-devel] [PATCH] x86/svm: Fix svm_vmcb_dump() when used in current context Andrew Cooper
2019-06-17 13:55 ` Jan Beulich
2019-06-17 13:59 ` Andrew Cooper [this message]
2019-06-19 16:23 ` Woods, Brian
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