From: David Laight <David.Laight@ACULAB.COM>
To: 'Jim Mattson' <jmattson@google.com>,
'Paolo Bonzini' <pbonzini@redhat.com>
Cc: 'LKML' <linux-kernel@vger.kernel.org>,
'kvm list' <kvm@vger.kernel.org>,
'Sean Christopherson' <sean.j.christopherson@intel.com>,
'Joerg Roedel' <joro@8bytes.org>,
"'everdox@gmail.com'" <everdox@gmail.com>
Subject: RE: [PATCH] KVM: x86: handle wrap around 32-bit address space
Date: Wed, 29 Apr 2020 08:56:12 +0000 [thread overview]
Message-ID: <91c76eb0edcd4f1a9d5bc541d35f8ade@AcuMS.aculab.com> (raw)
In-Reply-To: <c3ac5f4c9e3a412cb57ea02df19dd2d2@AcuMS.aculab.com>
From: David Laight
> Sent: 29 April 2020 09:50
> From: Jim Mattson
> > Sent: 28 April 2020 01:29
> > On Mon, Apr 27, 2020 at 9:59 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
> > >
> > > KVM is not handling the case where EIP wraps around the 32-bit address
> > > space (that is, outside long mode). This is needed both in vmx.c
> > > and in emulate.c. SVM with NRIPS is okay, but it can still print
> > > an error to dmesg due to integer overflow.
> ...
> > > + if (unlikely(((rip ^ orig_rip) >> 31) == 3) && !is_64_bit_mode(vcpu))
>
> Isn't the more obvious:
> if (((rip ^ orig_rip) & 1ull << 32) ...
> equivalent?
Actually not even being clever, how about:
if (orig_rip < (1ull << 32) && unlikely(rip >= (1ull << 32)) && ...
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2020-04-29 8:56 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-27 16:59 [PATCH] KVM: x86: handle wrap around 32-bit address space Paolo Bonzini
2020-04-28 0:28 ` Jim Mattson
2020-04-28 0:33 ` Sean Christopherson
2020-04-29 8:50 ` David Laight
2020-04-29 8:56 ` David Laight [this message]
2020-04-30 12:45 ` Paolo Bonzini
2020-04-30 13:18 ` David Laight
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