From: Peter Zijlstra <peterz@infradead.org>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Andy Lutomirski <luto@kernel.org>,
Jonathan Corbet <corbet@lwn.net>,
Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
tony.luck@intel.com, ak@linux.intel.com,
tim.c.chen@linux.intel.com, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, kvm@vger.kernel.org,
Alyssa Milburn <alyssa.milburn@linux.intel.com>,
Daniel Sneddon <daniel.sneddon@linux.intel.com>,
antonio.gomez.iglesias@linux.intel.com,
Alyssa Milburn <alyssa.milburn@intel.com>
Subject: Re: [RESEND][PATCH 1/6] x86/bugs: Add asm helpers for executing VERW
Date: Wed, 25 Oct 2023 10:02:13 +0200 [thread overview]
Message-ID: <20231025080213.GC37471@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <654468cf-1563-4c1c-8c7c-076bc6dfbabf@citrix.com>
On Wed, Oct 25, 2023 at 08:52:50AM +0100, Andrew Cooper wrote:
> > +.pushsection .entry.text, "ax"
> > +
> > +.align 64
> > +SYM_CODE_START_NOALIGN(mds_verw_sel)
> > + UNWIND_HINT_UNDEFINED
> > + ANNOTATE_NOENDBR
> > +1:
> > + .word __KERNEL_DS
> > + .skip 64 - (. - 1b), 0xcc
>
> The 1 label aliases mds_verw_sel and this must remain like this for the
> construct to work.
>
> So instead of .skip, why not simply .align 64, 0xcc and get rid of the
> 1: label?
Because I forgot you can add a filler byte to .align :/ Yes, that's much
saner.
> Do we have a suitably named constant cacheline size, rather than
> opencoding 64?
L1_CACHE_BYTES probably.
>
> > +SYM_CODE_END(mds_verw_sel);
>
> Given that KVM needs it, this probably needs an EXPORT_SYMBOL_GPL() on it.
localyesconfig ftw ;-)
/me runs
next prev parent reply other threads:[~2023-10-25 8:02 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-20 20:44 [PATCH 0/6] Delay VERW Pawan Gupta
2023-10-20 20:44 ` [PATCH 1/6] x86/bugs: Add asm helpers for executing VERW Pawan Gupta
2023-10-20 23:13 ` Sean Christopherson
2023-10-21 1:00 ` Pawan Gupta
2023-10-20 23:55 ` [RESEND][PATCH " Andrew Cooper
2023-10-21 1:18 ` Pawan Gupta
2023-10-21 1:33 ` Andrew Cooper
2023-10-21 2:21 ` Pawan Gupta
2023-10-23 18:08 ` Josh Poimboeuf
2023-10-23 19:09 ` Pawan Gupta
2023-10-25 6:28 ` Pawan Gupta
2023-10-25 7:22 ` Peter Zijlstra
2023-10-25 7:52 ` Andrew Cooper
2023-10-25 8:02 ` Peter Zijlstra [this message]
2023-10-25 15:27 ` Pawan Gupta
[not found] ` <6439a094-23a6-4de3-aa41-bd033163e044@citrix.com>
2023-10-22 16:16 ` [PATCH " Peter Zijlstra
2023-10-20 20:45 ` [PATCH 2/6] x86/entry_64: Add VERW just before userspace transition Pawan Gupta
2023-10-23 18:22 ` Josh Poimboeuf
2023-10-23 19:13 ` Pawan Gupta
2023-10-23 19:17 ` Dave Hansen
2023-10-23 18:35 ` Josh Poimboeuf
2023-10-23 21:04 ` Pawan Gupta
2023-10-23 21:47 ` Josh Poimboeuf
2023-10-23 22:30 ` Pawan Gupta
2023-10-23 22:45 ` Dave Hansen
2023-10-24 0:00 ` Pawan Gupta
2023-10-20 20:45 ` [PATCH 3/6] x86/entry_32: " Pawan Gupta
2023-10-20 23:49 ` Andi Kleen
2023-10-21 1:28 ` Pawan Gupta
2023-10-20 20:45 ` [PATCH 4/6] x86/bugs: Use ALTERNATIVE() instead of mds_user_clear static key Pawan Gupta
2023-10-23 18:48 ` Josh Poimboeuf
2023-10-23 21:09 ` Pawan Gupta
2023-10-20 20:45 ` [PATCH 5/6] x86/bugs: Cleanup mds_user_clear Pawan Gupta
2023-10-23 8:51 ` Nikolay Borisov
2023-10-23 16:06 ` Pawan Gupta
2023-10-20 20:45 ` [PATCH 6/6] KVM: VMX: Move VERW closer to VMentry for MDS mitigation Pawan Gupta
2023-10-20 22:55 ` Sean Christopherson
2023-10-21 0:46 ` Pawan Gupta
2023-10-23 14:58 ` Sean Christopherson
2023-10-23 17:05 ` Pawan Gupta
2023-10-23 18:56 ` Josh Poimboeuf
2023-10-23 21:17 ` Pawan Gupta
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