linux-kernel - Re: [CFT PATCH v2 0/2] KVM: support XSAVES usage in the host

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 25 Nov 2014 16:50:06 +0200
From:	Nadav Amit <nadav.amit@...il.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
Cc:	Wanpeng Li <wanpeng.li@...ux.intel.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	kvm list <kvm@...r.kernel.org>,
	Nadav Amit <namit@...technion.ac.il>, hpa@...ux.intel.com
Subject: Re: [CFT PATCH v2 0/2] KVM: support XSAVES usage in the host


> On Nov 25, 2014, at 16:17, Paolo Bonzini <pbonzini@...hat.com> wrote:
> 
> 
> 
> On 25/11/2014 15:05, Nadav Amit wrote:
>>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>>> index 373b0ab9a32e..ca26681455c2 100644
>>> --- a/arch/x86/kvm/x86.c
>>> +++ b/arch/x86/kvm/x86.c
>>> @@ -6955,6 +6955,9 @@ int fx_init(struct kvm_vcpu *vcpu)
>>> 		return err;
>>> 
>>> 	fpu_finit(&vcpu->arch.guest_fpu);
>>> +	if (cpu_has_xsaves)
>>> +		vcpu->arch.guest_fpu.state->xsave.xsave_hdr.xcomp_bv =
>>> +			host_xcr0 | XSTATE_COMPACTION_ENABLED;
>>> 
>>> 	/*
>>> 	 * Ensure guest xcr0 is valid for loading
>> 
>> The second version works for me (w/qemu v2.1.0; Linux 3.13 guest). I
>> did not need to apply this patch on top. [although I am not sure whether
>> relying on userspace to call KVM_SET_XSAVE early enough is a good practice].
> 
> Did you actually try the patch? :)  If it works, I'm tempted to apply it
> anyway.
Yes, I tried it both with and without this patch.
Due to time constraints I only tested minimal functionality (Linux boot).
I will run more tests in the near future. Anyhow, you can put the:

Tested-by: Nadav Amit <namit@...technion.ac.il>

> 
>> One disclaimer: Since I got limited time with the machine, I executed
>> a slightly modified kernel/qemu, and not the latest version.
>> Anyhow, I don’t think these differences can have any impact.
> 
> Yes, that is no problem.

I am just worried that Wanpeng reported it fails, while I report it works...

Nadav

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/