linux-kernel - Re: [PATCH] KVM: x86: move guest_pv_has out of user

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Message-ID: <e0a60cc65d6e3d7670b65479fd7ff662db6a5dfd.camel@infradead.org>
Date:   Fri, 12 Nov 2021 08:11:07 +0000
From:   David Woodhouse <dwmw2@...radead.org>
To:     Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Stephen Rothwell <sfr@...b.auug.org.au>
Subject: Re: [PATCH] KVM: x86: move guest_pv_has out of user_access section

On Fri, 2021-11-12 at 02:54 -0500, Paolo Bonzini wrote:
> When UBSAN is enabled, the code emitted for the call to guest_pv_has
> includes a call to __ubsan_handle_load_invalid_value.  objtool
> complains that this call happens with UACCESS enabled; to avoid
> the warning, pull the calls to user_access_begin into both arms
> of the "if" statement, after the check for guest_pv_has.
> 
> Reported-by: Stephen Rothwell <sfr@...b.auug.org.au>
> Cc: David Woodhouse <dwmw2@...radead.org>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>

Acked-by: David Woodhouse <dwmw@...zon.co.uk>

Thanks. I found a bunch of those objtool warnings during my original
experimentation and testing, but clearly missed that one. I'll turn on
CONFIG_UBSAN.



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