From: Ingo Molnar <mingo@elte.hu>
To: Avi Kivity <avi@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
Joerg Roedel <joerg.roedel@amd.com>,
Benjamin Serebrin <benjamin.serebrin@amd.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
kvm@vger.kernel.org, Alexander Graf <agraf@suse.de>,
Arjan van de Ven <arjan@infradead.org>,
Alexander van Heukelum <heukelum@fastmail.fm>
Subject: Re: kvm vmload/vmsave vs tss.ist
Date: Thu, 25 Dec 2008 17:42:32 +0100 [thread overview]
Message-ID: <20081225164232.GA25195@elte.hu> (raw)
In-Reply-To: <20081225162107.GB14486@elte.hu>
* Ingo Molnar <mingo@elte.hu> wrote:
> i'd suggest to reuse the irq-stacks for this. Right now on 64-bit we've
> got the following stack layout: 8K process stacks, a 16K IRQ stack on
> each CPU, shared by all IRQs. Then we have the IST stacks with weird
> sizes: debug:8K, the others: 4K.
this has to be done carefully though, as there's a subtle detail here:
right now the pda_irqcount and the pda_irqstackptr logic in entry_64.S is
not re-entry safe and relies on IRQs being off.
If critical exceptions are moved to the IRQ stack then %rsp switching to
the IRQ stack has to be done atomically: instead of using the pda_irqcount
check the %rsp value itself should be checked against pda_irqstackptr - if
it's within that 16K range then we are already on the IRQ stack and do not
need to switch to it but can just use the current %rsp.
Ingo
next prev parent reply other threads:[~2008-12-25 16:42 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-25 14:59 kvm vmload/vmsave vs tss.ist Avi Kivity
2008-12-25 15:17 ` Ingo Molnar
2008-12-25 15:46 ` Avi Kivity
2008-12-25 16:21 ` Ingo Molnar
2008-12-25 16:42 ` Ingo Molnar [this message]
2008-12-25 17:40 ` Avi Kivity
2008-12-25 17:58 ` Ingo Molnar
2008-12-25 18:12 ` Avi Kivity
2008-12-25 18:18 ` Ingo Molnar
2008-12-25 18:19 ` Avi Kivity
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