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From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	David Laight <David.Laight@ACULAB.COM>,
	Arvind Sankar <nivedita@alum.mit.edu>
Subject: Re: [PATCH v2 2/2] KVM: x86/mmu: Micro-optimize nEPT's bad memptype/XWR checks
Date: Wed, 15 Jan 2020 19:17:27 +0100	[thread overview]
Message-ID: <f23a2801-d33d-4c2d-290e-60b0fa142cb5@redhat.com> (raw)
In-Reply-To: <20200110160453.GA21485@linux.intel.com>

On 10/01/20 17:04, Sean Christopherson wrote:
> Ya, I don't love the code, but it was the least awful of the options I
> tried, in that it's the most readable without being too obnoxious.
> 
> 
> Similar to your suggestion, but it avoids evaluating __is_bad_mt_xwr() if
> reserved bits are set, which is admittedly rare.
> 
> 	return __is_rsvd_bits_set(&mmu->guest_rsvd_check, gpte, level)
> #if PTTYPE == PTTYPE_EPT
> 	       || __is_bad_mt_xwr(&mmu->guest_rsvd_check, gpte)
> #endif
> 	       ;
> 
> Or macrofying the call to keep the call site clean, but IMO this obfuscates
> things too much.
> 
> 	return __is_rsvd_bits_set(&mmu->guest_rsvd_check, gpte, level) ||
> 	       IS_BAD_MT_XWR(&mmu->guest_rsvd_check, gpte);

I think what you posted is the best (David's comes second).

Queued, thanks.

Paolo


      parent reply	other threads:[~2020-01-15 18:17 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-09 23:06 [PATCH v2 0/2] KVM: x86/mmu: Optimize rsvd pte checks Sean Christopherson
2020-01-09 23:06 ` [PATCH v2 1/2] KVM: x86/mmu: Reorder the reserved bit check in prefetch_invalid_gpte() Sean Christopherson
2020-01-10 11:37   ` Vitaly Kuznetsov
2020-01-09 23:06 ` [PATCH v2 2/2] KVM: x86/mmu: Micro-optimize nEPT's bad memptype/XWR checks Sean Christopherson
2020-01-10 11:37   ` Vitaly Kuznetsov
2020-01-10 16:04     ` Sean Christopherson
2020-01-10 16:13       ` David Laight
2020-01-15 18:17       ` Paolo Bonzini [this message]

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