linux-kernel - Re: ping Re: [PATCH v4 0/2] x86: Fix ARCH_REQ_XCOMP

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Message-ID: <877d8kakwg.ffs@tglx>
Date:   Wed, 23 Mar 2022 13:55:11 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Paolo Bonzini <bonzini@....org>, dave.hansen@...ux.intel.com
Cc:     yang.zhong@...el.com, ravi.v.shankar@...el.com, mingo@...hat.com,
        "Chang S. Bae" <chang.seok.bae@...el.com>, bp@...en8.de,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        KVM list <kvm@...r.kernel.org>
Subject: Re: ping Re: [PATCH v4 0/2] x86: Fix ARCH_REQ_XCOMP_PERM and update
 the test

On Wed, Mar 23 2022 at 13:27, Thomas Gleixner wrote:
> On Wed, Mar 23 2022 at 12:04, Paolo Bonzini wrote:
>> can this series be included in 5.18 and CCed to stable?
>
> working on it. There is another issue with that which I'm currently
> looking into.

The size calculation for the kernel state fails to take supervisor
states into account. Up to 5.18 that did not matter because ENQCMD/PASID
was disabled. But now it matters...

Thanks,

        tglx
---

--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1625,6 +1625,8 @@ static int __xstate_request_perm(u64 per
 
 	/* Calculate the resulting kernel state size */
 	mask = permitted | requested;
+	/* Take supervisor states into account */
+	mask |= xfeatures_mask_supervisor();
 	ksize = xstate_calculate_size(mask, compacted);
 
 	/* Calculate the resulting user state size */