Re: [PATCH 0/4] Add support for XMM fast hypercalls
From: Siddharth Chandrasekaran <hidden>
Date: 2021-04-08 15:40:33
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On Thu, Apr 08, 2021 at 05:30:26PM +0200, Paolo Bonzini wrote:
CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe. On 08/04/21 17:28, Wei Liu wrote:quoted
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Although the Hyper-v TLFS mentions that a guest cannot use this feature unless the hypervisor advertises support for it, some hypercalls which we plan on upstreaming in future uses them anyway.No, please don't do this. Check the feature bit(s) before you issue hypercalls which rely on the extended interface.Perhaps Siddharth should clarify this, but I read it as Hyper-V being buggy and using XMM arguments unconditionally.
The guest is at fault here as it expects Hyper-V to consume arguments from XMM registers for certain hypercalls (that we are working) even if we didn't expose the feature via CPUID bits. ~ Sid. Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B Sitz: Berlin Ust-ID: DE 289 237 879