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Commit 8d31bc35 authored by Pawan Gupta's avatar Pawan Gupta Committed by Yongqiang Liu
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x86/speculation/mmio: Enable CPU Fill buffer clearing on idle

stable inclusion
from stable-v4.19.248
commit 8b42145e8c9903d4805651e08f4fca628e166642
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5D5RS


CVE: CVE-2022-21123,CVE-2022-21125,CVE-2022-21166

--------------------------------

commit 99a83db5a605137424e1efe29dc0573d6a5b6316 upstream

When the CPU is affected by Processor MMIO Stale Data vulnerabilities,
Fill Buffer Stale Data Propagator (FBSDP) can propagate stale data out
of Fill buffer to uncore buffer when CPU goes idle. Stale data can then
be exploited with other variants using MMIO operations.

Mitigate it by clearing the Fill buffer before entering idle state.

Signed-off-by: default avatarPawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Co-developed-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarThadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarYipeng Zou <zouyipeng@huawei.com>
Reviewed-by: default avatarZhang Jianhua <chris.zjh@huawei.com>
Reviewed-by: default avatarLiao Chang <liaochang1@huawei.com>
Signed-off-by: default avatarYongqiang Liu <liuyongqiang13@huawei.com>
parent 8e8722cd
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......@@ -416,6 +416,14 @@ static void __init mmio_select_mitigation(void)
else
static_branch_enable(&mmio_stale_data_clear);
/*
* If Processor-MMIO-Stale-Data bug is present and Fill Buffer data can
* be propagated to uncore buffers, clearing the Fill buffers on idle
* is required irrespective of SMT state.
*/
if (!(ia32_cap & ARCH_CAP_FBSDP_NO))
static_branch_enable(&mds_idle_clear);
/*
* Check if the system has the right microcode.
*
......@@ -1182,6 +1190,8 @@ static void update_indir_branch_cond(void)
/* Update the static key controlling the MDS CPU buffer clear in idle */
static void update_mds_branch_idle(void)
{
u64 ia32_cap = x86_read_arch_cap_msr();
/*
* Enable the idle clearing if SMT is active on CPUs which are
* affected only by MSBDS and not any other MDS variant.
......@@ -1193,10 +1203,12 @@ static void update_mds_branch_idle(void)
if (!boot_cpu_has_bug(X86_BUG_MSBDS_ONLY))
return;
if (sched_smt_active())
if (sched_smt_active()) {
static_branch_enable(&mds_idle_clear);
else
} else if (mmio_mitigation == MMIO_MITIGATION_OFF ||
(ia32_cap & ARCH_CAP_FBSDP_NO)) {
static_branch_disable(&mds_idle_clear);
}
}
#define MDS_MSG_SMT "MDS CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for more details.\n"
......
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