From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Jon Masters <jcm@redhat.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@suse.de>, Ingo Molnar <mingo@kernel.org>,
David Woodhouse <dwmw@amazon.co.uk>,
"Srivatsa S. Bhat" <srivatsa@csail.mit.edu>,
"Matt Helsley (VMware)" <matt.helsley@gmail.com>,
Alexey Makhalov <amakhalov@vmware.com>, Bo Gan <ganb@vmware.com>
Subject: [PATCH 4.4 051/107] x86/bugs: Read SPEC_CTRL MSR during boot and re-use reserved bits
Date: Mon, 23 Jul 2018 14:41:45 +0200 [thread overview]
Message-ID: <20180723122415.520868834@linuxfoundation.org> (raw)
In-Reply-To: <20180723122413.003644357@linuxfoundation.org>
4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
commit 1b86883ccb8d5d9506529d42dbe1a5257cb30b18 upstream
The 336996-Speculative-Execution-Side-Channel-Mitigations.pdf refers to all
the other bits as reserved. The Intel SDM glossary defines reserved as
implementation specific - aka unknown.
As such at bootup this must be taken it into account and proper masking for
the bits in use applied.
A copy of this document is available at
https://bugzilla.kernel.org/show_bug.cgi?id=199511
[ tglx: Made x86_spec_ctrl_base __ro_after_init ]
[ Srivatsa: Removed __ro_after_init for 4.4.y ]
Suggested-by: Jon Masters <jcm@redhat.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa@csail.mit.edu>
Reviewed-by: Matt Helsley (VMware) <matt.helsley@gmail.com>
Reviewed-by: Alexey Makhalov <amakhalov@vmware.com>
Reviewed-by: Bo Gan <ganb@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/include/asm/nospec-branch.h | 24 ++++++++++++++++++++----
arch/x86/kernel/cpu/bugs.c | 27 +++++++++++++++++++++++++++
2 files changed, 47 insertions(+), 4 deletions(-)
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -172,6 +172,17 @@ enum spectre_v2_mitigation {
SPECTRE_V2_IBRS,
};
+/*
+ * The Intel specification for the SPEC_CTRL MSR requires that we
+ * preserve any already set reserved bits at boot time (e.g. for
+ * future additions that this kernel is not currently aware of).
+ * We then set any additional mitigation bits that we want
+ * ourselves and always use this as the base for SPEC_CTRL.
+ * We also use this when handling guest entry/exit as below.
+ */
+extern void x86_spec_ctrl_set(u64);
+extern u64 x86_spec_ctrl_get_default(void);
+
extern char __indirect_thunk_start[];
extern char __indirect_thunk_end[];
@@ -208,8 +219,9 @@ void alternative_msr_write(unsigned int
static inline void indirect_branch_prediction_barrier(void)
{
- alternative_msr_write(MSR_IA32_PRED_CMD, PRED_CMD_IBPB,
- X86_FEATURE_USE_IBPB);
+ u64 val = PRED_CMD_IBPB;
+
+ alternative_msr_write(MSR_IA32_PRED_CMD, val, X86_FEATURE_USE_IBPB);
}
/*
@@ -220,14 +232,18 @@ static inline void indirect_branch_predi
*/
#define firmware_restrict_branch_speculation_start() \
do { \
+ u64 val = x86_spec_ctrl_get_default() | SPEC_CTRL_IBRS; \
+ \
preempt_disable(); \
- alternative_msr_write(MSR_IA32_SPEC_CTRL, SPEC_CTRL_IBRS, \
+ alternative_msr_write(MSR_IA32_SPEC_CTRL, val, \
X86_FEATURE_USE_IBRS_FW); \
} while (0)
#define firmware_restrict_branch_speculation_end() \
do { \
- alternative_msr_write(MSR_IA32_SPEC_CTRL, 0, \
+ u64 val = x86_spec_ctrl_get_default(); \
+ \
+ alternative_msr_write(MSR_IA32_SPEC_CTRL, val, \
X86_FEATURE_USE_IBRS_FW); \
preempt_enable(); \
} while (0)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -27,6 +27,12 @@
static void __init spectre_v2_select_mitigation(void);
+/*
+ * Our boot-time value of the SPEC_CTRL MSR. We read it once so that any
+ * writes to SPEC_CTRL contain whatever reserved bits have been set.
+ */
+static u64 x86_spec_ctrl_base;
+
void __init check_bugs(void)
{
identify_boot_cpu();
@@ -36,6 +42,13 @@ void __init check_bugs(void)
print_cpu_info(&boot_cpu_data);
}
+ /*
+ * Read the SPEC_CTRL MSR to account for reserved bits which may
+ * have unknown values.
+ */
+ if (boot_cpu_has(X86_FEATURE_IBRS))
+ rdmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
+
/* Select the proper spectre mitigation before patching alternatives */
spectre_v2_select_mitigation();
@@ -94,6 +107,20 @@ static const char *spectre_v2_strings[]
static enum spectre_v2_mitigation spectre_v2_enabled = SPECTRE_V2_NONE;
+void x86_spec_ctrl_set(u64 val)
+{
+ if (val & ~SPEC_CTRL_IBRS)
+ WARN_ONCE(1, "SPEC_CTRL MSR value 0x%16llx is unknown.\n", val);
+ else
+ wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base | val);
+}
+EXPORT_SYMBOL_GPL(x86_spec_ctrl_set);
+
+u64 x86_spec_ctrl_get_default(void)
+{
+ return x86_spec_ctrl_base;
+}
+EXPORT_SYMBOL_GPL(x86_spec_ctrl_get_default);
#ifdef RETPOLINE
static bool spectre_v2_bad_module;
next prev parent reply other threads:[~2018-07-23 12:46 UTC|newest]
Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-23 12:40 [PATCH 4.4 000/107] 4.4.144-stable review Greg Kroah-Hartman
2018-07-23 12:40 ` [PATCH 4.4 002/107] x86/MCE: Remove min interval polling limitation Greg Kroah-Hartman
2018-07-23 12:40 ` [PATCH 4.4 003/107] fat: fix memory allocation failure handling of match_strdup() Greg Kroah-Hartman
2018-07-23 12:40 ` [PATCH 4.4 004/107] ALSA: rawmidi: Change resized buffers atomically Greg Kroah-Hartman
2018-07-23 12:40 ` [PATCH 4.4 005/107] ARC: Fix CONFIG_SWAP Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 006/107] ARC: mm: allow mprotect to make stack mappings executable Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 007/107] mm: memcg: fix use after free in mem_cgroup_iter() Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 008/107] ipv4: Return EINVAL when ping_group_range sysctl doesnt map to user ns Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 009/107] ipv6: fix useless rol32 call on hash Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 010/107] lib/rhashtable: consider param->min_size when setting initial table size Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 011/107] net/ipv4: Set oif in fib_compute_spec_dst Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 012/107] net: phy: fix flag masking in __set_phy_supported Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 013/107] ptp: fix missing break in switch Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 014/107] tg3: Add higher cpu clock for 5762 Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 015/107] net: Dont copy pfmemalloc flag in __copy_skb_header() Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 016/107] skbuff: Unconditionally copy pfmemalloc in __skb_clone() Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 017/107] xhci: Fix perceived dead host due to runtime suspend race with event handler Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 018/107] x86/paravirt: Make native_save_fl() extern inline Greg Kroah-Hartman
2018-08-24 23:08 ` Ben Hutchings
2018-08-27 21:06 ` Nick Desaulniers
2018-07-23 12:41 ` [PATCH 4.4 019/107] x86/cpufeatures: Add CPUID_7_EDX CPUID leaf Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 020/107] x86/cpufeatures: Add Intel feature bits for Speculation Control Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 021/107] x86/cpufeatures: Add AMD " Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 022/107] x86/msr: Add definitions for new speculation control MSRs Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 023/107] x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 024/107] x86/cpufeature: Blacklist SPEC_CTRL/PRED_CMD on early Spectre v2 microcodes Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 025/107] x86/speculation: Add basic IBPB (Indirect Branch Prediction Barrier) support Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 026/107] x86/cpufeatures: Clean up Spectre v2 related CPUID flags Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 027/107] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 028/107] x86/pti: Mark constant arrays as __initconst Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 029/107] x86/asm/entry/32: Simplify pushes of zeroed pt_regs->REGs Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 030/107] x86/entry/64/compat: Clear registers for compat syscalls, to reduce speculation attack surface Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 031/107] x86/speculation: Update Speculation Control microcode blacklist Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 032/107] x86/speculation: Correct Speculation Control microcode blacklist again Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 033/107] x86/speculation: Clean up various Spectre related details Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 034/107] x86/speculation: Fix up array_index_nospec_mask() asm constraint Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 035/107] x86/speculation: Add <asm/msr-index.h> dependency Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 036/107] x86/xen: Zero MSR_IA32_SPEC_CTRL before suspend Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 037/107] x86/mm: Factor out LDT init from context init Greg Kroah-Hartman
2018-08-24 23:44 ` Ben Hutchings
2018-08-26 6:06 ` Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 038/107] x86/mm: Give each mm TLB flush generation a unique ID Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 041/107] x86/speculation: Use IBRS if available before calling into firmware Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 042/107] x86/speculation: Move firmware_restrict_branch_speculation_*() from C to CPP Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 043/107] x86/speculation: Remove Skylake C2 from Speculation Control microcode blacklist Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 046/107] xen: set cpu capabilities from xen_start_kernel() Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 047/107] x86/amd: dont set X86_BUG_SYSRET_SS_ATTRS when running under Xen Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 048/107] x86/nospec: Simplify alternative_msr_write() Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 049/107] x86/bugs: Concentrate bug detection into a separate function Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 050/107] x86/bugs: Concentrate bug reporting " Greg Kroah-Hartman
2018-07-23 12:41 ` Greg Kroah-Hartman [this message]
2018-07-23 12:41 ` [PATCH 4.4 052/107] x86/bugs, KVM: Support the combination of guest and host IBRS Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 053/107] x86/cpu: Rename Merrifield2 to Moorefield Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 054/107] x86/cpu/intel: Add Knights Mill to Intel family Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 055/107] x86/bugs: Expose /sys/../spec_store_bypass Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 056/107] x86/cpufeatures: Add X86_FEATURE_RDS Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 057/107] x86/bugs: Provide boot parameters for the spec_store_bypass_disable mitigation Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 058/107] x86/bugs/intel: Set proper CPU features and setup RDS Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 059/107] x86/bugs: Whitelist allowed SPEC_CTRL MSR values Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 060/107] x86/bugs/AMD: Add support to disable RDS on Fam[15, 16, 17]h if requested Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 061/107] x86/speculation: Create spec-ctrl.h to avoid include hell Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 062/107] prctl: Add speculation control prctls Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 063/107] x86/process: Optimize TIF checks in __switch_to_xtra() Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 064/107] x86/process: Correct and optimize TIF_BLOCKSTEP switch Greg Kroah-Hartman
2018-07-23 12:41 ` [PATCH 4.4 065/107] x86/process: Optimize TIF_NOTSC switch Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 066/107] x86/process: Allow runtime control of Speculative Store Bypass Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 067/107] x86/speculation: Add prctl for Speculative Store Bypass mitigation Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 068/107] nospec: Allow getting/setting on non-current task Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 069/107] proc: Provide details on speculation flaw mitigations Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 070/107] seccomp: Enable " Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 071/107] prctl: Add force disable speculation Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 072/107] seccomp: Use PR_SPEC_FORCE_DISABLE Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 073/107] seccomp: Add filter flag to opt-out of SSB mitigation Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 074/107] seccomp: Move speculation migitation control to arch code Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 075/107] x86/speculation: Make "seccomp" the default mode for Speculative Store Bypass Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 076/107] x86/bugs: Rename _RDS to _SSBD Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 077/107] proc: Use underscores for SSBD in status Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 078/107] Documentation/spec_ctrl: Do some minor cleanups Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 079/107] x86/bugs: Fix __ssb_select_mitigation() return type Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 080/107] x86/bugs: Make cpu_show_common() static Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 081/107] x86/bugs: Fix the parameters alignment and missing void Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 082/107] x86/cpu: Make alternative_msr_write work for 32-bit code Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 084/107] x86/cpufeatures: Disentangle MSR_SPEC_CTRL enumeration from IBRS Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 085/107] x86/cpufeatures: Disentangle SSBD enumeration Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 086/107] x86/cpu/AMD: Fix erratum 1076 (CPB bit) Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 087/107] x86/cpufeatures: Add FEATURE_ZEN Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 088/107] x86/speculation: Handle HT correctly on AMD Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 089/107] x86/bugs, KVM: Extend speculation control for VIRT_SPEC_CTRL Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 090/107] x86/speculation: Add virtualized speculative store bypass disable support Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 091/107] x86/speculation: Rework speculative_store_bypass_update() Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 092/107] x86/bugs: Unify x86_spec_ctrl_{set_guest, restore_host} Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 093/107] x86/bugs: Expose x86_spec_ctrl_base directly Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 094/107] x86/bugs: Remove x86_spec_ctrl_set() Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 095/107] x86/bugs: Rework spec_ctrl base and mask logic Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 096/107] x86/speculation, KVM: Implement support for VIRT_SPEC_CTRL/LS_CFG Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 097/107] x86/bugs: Rename SSBD_NO to SSB_NO Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 098/107] x86/xen: Add call of speculative_store_bypass_ht_init() to PV paths Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 099/107] x86/cpu: Re-apply forced caps every time CPU caps are re-read Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 100/107] block: do not use interruptible wait anywhere Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 101/107] clk: tegra: Fix PLL_U post divider and initial rate on Tegra30 Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 102/107] ubi: Introduce vol_ignored() Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 103/107] ubi: Rework Fastmap attach base code Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 104/107] ubi: Be more paranoid while seaching for the most recent Fastmap Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 105/107] ubi: Fix races around ubi_refill_pools() Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 106/107] ubi: Fix Fastmaps update_vol() Greg Kroah-Hartman
2018-07-23 12:42 ` [PATCH 4.4 107/107] ubi: fastmap: Erase outdated anchor PEBs during attach Greg Kroah-Hartman
2018-09-04 18:39 ` Ben Hutchings
2018-09-17 11:53 ` Greg Kroah-Hartman
2018-07-23 15:11 ` [PATCH 4.4 000/107] 4.4.144-stable review Nathan Chancellor
2018-07-23 22:14 ` Dan Rue
2018-07-24 15:57 ` Guenter Roeck
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