From: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
To: Maxim Levitsky <mlevitsk@redhat.com>
Cc: kvm@vger.kernel.org, Borislav Petkov <bp@alien8.de>,
"open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<linux-kernel@vger.kernel.org>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, Paolo Bonzini <pbonzini@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Joerg Roedel <joro@8bytes.org>, "H. Peter Anvin" <hpa@zytor.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Ingo Molnar <mingo@redhat.com>,
Qian Cai <cai@redhat.com>
Subject: Re: [PATCH] KVM: x86: use positive error values for msr emulation that causes #GP
Date: Thu, 5 Nov 2020 11:00:53 +0100 [thread overview]
Message-ID: <CAM9Jb+gCoxFXh3oBnZhj8LJ6PoAy0wmQuKHR5p=sqGHyqsUe8A@mail.gmail.com> (raw)
In-Reply-To: <e177d0497f08173e7991341796aa21c2dd2ba86b.camel@redhat.com>
> > This looks good to me. This should solve "-EPERM" return by "__kvm_set_msr" .
> >
> > A question I have, In the case of "kvm_emulate_rdmsr()", for "r" we
> > are injecting #GP.
> > Is there any possibility of this check to be hit and still result in #GP?
>
> When I wrote this patch series I assumed that msr reads usually don't have
> side effects so they shouldn't fail, and fixed only the msr write code path
> to deal with negative errors. Now that you put this in this light,
> I do think that you are right and I should have added code for both msr reads and writes
> especially to catch cases in which negative errors are returned by mistake
> like this one (my mistake in this case since my patch series was merged
> after the userspace msrs patch series).
>
> What do you think?
>
> I can prepare a separate patch for this, which should go to the next
> kernel version since this doesn't fix a regression.
Patch on the top should be okay. I think.
Thanks,
Pankaj
prev parent reply other threads:[~2020-11-05 10:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-01 11:55 [PATCH] KVM: x86: use positive error values for msr emulation that causes #GP Maxim Levitsky
2020-11-04 16:31 ` Qian Cai
2020-11-04 16:40 ` Paolo Bonzini
2020-11-05 6:14 ` Pankaj Gupta
2020-11-05 9:07 ` Maxim Levitsky
2020-11-05 10:00 ` Pankaj Gupta [this message]
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