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Date: Mon, 23 Apr 2018 21:08:49 +0200
From: Borislav Petkov <bp@suse.de>
Subject: [MODERATED] Re: [PATCH v3 06/10] [PATCH v3 6/9] Linux Patch #6
Message-ID: <20180423190849.GN24245@pd.tnic>
References: <20180423171426.795385641@dhcp-10-159-147-220.vpn.oracle.com>
 <20180423185755.GM24245@pd.tnic>
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To: speck@linutronix.de
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On Mon, Apr 23, 2018 at 08:57:55PM +0200, Borislav Petkov wrote:
> Something's still fishy with this patch. I'm booting a guest with
>=20
> spec_store_bypass_disable=3Don
>=20
> but dmesg still says:
>=20
> [    0.044001] Speculative Store Bypass: Vulnerable

Ok, there it is:

static enum spec_store_bypass_mitigation_cmd __init spec_store_bypass_parse_c=
mdline(void)
{
        char arg[20];
        int ret, i;
        enum spec_store_bypass_mitigation_cmd cmd =3D SPEC_STORE_BYPASS_CMD_A=
UTO;

        if (!boot_cpu_has_bug(X86_BUG_CPU_SPEC_STORE_BYPASS)) {
                return SPEC_STORE_BYPASS_CMD_NONE;

It needs to be

	if (!boot_cpu_has_bug(X86_BUG_CPU_SPEC_STORE_BYPASS))

not

	if (!boot_cpu_has(X86_FEATURE_STBUF_BYPASS))

which we set earlier in cpu_set_bug_bits().

Which makes me wonder why we even need X86_FEATURE_STBUF_BYPASS?

Or why we need X86_BUG_CPU_SPEC_STORE_BYPASS?

One of the two is superfluous AFAICT.

--=20
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imend=C3=B6rffer, Jane Smithard, Graham Norton, HR=
B 21284 (AG N=C3=BCrnberg)
--=20