diff options
Diffstat (limited to 'system/xen/xsa/xsa305-4.12-2.patch')
| -rw-r--r-- | system/xen/xsa/xsa305-4.12-2.patch | 192 |
1 files changed, 0 insertions, 192 deletions
diff --git a/system/xen/xsa/xsa305-4.12-2.patch b/system/xen/xsa/xsa305-4.12-2.patch deleted file mode 100644 index 07fba86287f8a..0000000000000 --- a/system/xen/xsa/xsa305-4.12-2.patch +++ /dev/null @@ -1,192 +0,0 @@ -From: Andrew Cooper <andrew.cooper3@citrix.com> -Subject: x86/spec-ctrl: Mitigate the TSX Asynchronous Abort sidechannel - -See patch documentation and comments. - -This is part of XSA-305 / CVE-2019-11135 - -Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> -Reviewed-by: Jan Beulich <jbeulich@suse.com> - -diff --git a/docs/misc/xen-command-line.pandoc b/docs/misc/xen-command-line.pandoc -index b7e1bf8e8b..74e1e35b88 100644 ---- a/docs/misc/xen-command-line.pandoc -+++ b/docs/misc/xen-command-line.pandoc -@@ -1920,7 +1920,7 @@ extreme care.** - An overall boolean value, `spec-ctrl=no`, can be specified to turn off all - mitigations, including pieces of infrastructure used to virtualise certain - mitigation features for guests. This also includes settings which `xpti`, --`smt`, `pv-l1tf` control, unless the respective option(s) have been -+`smt`, `pv-l1tf`, `tsx` control, unless the respective option(s) have been - specified earlier on the command line. - - Alternatively, a slightly more restricted `spec-ctrl=no-xen` can be used to -@@ -2037,7 +2037,7 @@ Xen version. - = <bool> - - Applicability: x86 -- Default: true -+ Default: false on parts vulnerable to TAA, true otherwise - - Controls for the use of Transactional Synchronization eXtensions. - -@@ -2047,6 +2047,19 @@ a control has been introduced which allows TSX to be turned off. - On systems with the ability to turn TSX off, this boolean offers system wide - control of whether TSX is enabled or disabled. - -+On parts vulnerable to CVE-2019-11135 / TSX Asynchronous Abort, the following -+logic applies: -+ -+ * An explicit `tsx=` choice is honoured, even if it is `true` and would -+ result in a vulnerable system. -+ -+ * When no explicit `tsx=` choice is given, parts vulnerable to TAA will be -+ mitigated by disabling TSX, as this is the lowest overhead option. -+ -+ * If the use of TSX is important, the more expensive TAA mitigations can be -+ opted in to with `smt=0 spec-ctrl=md-clear`, at which point TSX will remain -+ active by default. -+ - ### ucode (x86) - > `= [<integer> | scan]` - -diff --git a/xen/arch/x86/spec_ctrl.c b/xen/arch/x86/spec_ctrl.c -index b37d40e643..800139d79c 100644 ---- a/xen/arch/x86/spec_ctrl.c -+++ b/xen/arch/x86/spec_ctrl.c -@@ -96,6 +96,9 @@ static int __init parse_spec_ctrl(const char *s) - if ( opt_pv_l1tf_domu < 0 ) - opt_pv_l1tf_domu = 0; - -+ if ( opt_tsx == -1 ) -+ opt_tsx = -3; -+ - disable_common: - opt_rsb_pv = false; - opt_rsb_hvm = false; -@@ -306,7 +309,7 @@ static void __init print_details(enum ind_thunk thunk, uint64_t caps) - printk("Speculative mitigation facilities:\n"); - - /* Hardware features which pertain to speculative mitigations. */ -- printk(" Hardware features:%s%s%s%s%s%s%s%s%s%s%s%s\n", -+ printk(" Hardware features:%s%s%s%s%s%s%s%s%s%s%s%s%s%s\n", - (_7d0 & cpufeat_mask(X86_FEATURE_IBRSB)) ? " IBRS/IBPB" : "", - (_7d0 & cpufeat_mask(X86_FEATURE_STIBP)) ? " STIBP" : "", - (_7d0 & cpufeat_mask(X86_FEATURE_L1D_FLUSH)) ? " L1D_FLUSH" : "", -@@ -318,7 +321,9 @@ static void __init print_details(enum ind_thunk thunk, uint64_t caps) - (caps & ARCH_CAPS_RSBA) ? " RSBA" : "", - (caps & ARCH_CAPS_SKIP_L1DFL) ? " SKIP_L1DFL": "", - (caps & ARCH_CAPS_SSB_NO) ? " SSB_NO" : "", -- (caps & ARCH_CAPS_MDS_NO) ? " MDS_NO" : ""); -+ (caps & ARCH_CAPS_MDS_NO) ? " MDS_NO" : "", -+ (caps & ARCH_CAPS_TSX_CTRL) ? " TSX_CTRL" : "", -+ (caps & ARCH_CAPS_TAA_NO) ? " TAA_NO" : ""); - - /* Compiled-in support which pertains to mitigations. */ - if ( IS_ENABLED(CONFIG_INDIRECT_THUNK) || IS_ENABLED(CONFIG_SHADOW_PAGING) ) -@@ -332,7 +337,7 @@ static void __init print_details(enum ind_thunk thunk, uint64_t caps) - "\n"); - - /* Settings for Xen's protection, irrespective of guests. */ -- printk(" Xen settings: BTI-Thunk %s, SPEC_CTRL: %s%s, Other:%s%s%s\n", -+ printk(" Xen settings: BTI-Thunk %s, SPEC_CTRL: %s%s%s, Other:%s%s%s\n", - thunk == THUNK_NONE ? "N/A" : - thunk == THUNK_RETPOLINE ? "RETPOLINE" : - thunk == THUNK_LFENCE ? "LFENCE" : -@@ -341,6 +346,8 @@ static void __init print_details(enum ind_thunk thunk, uint64_t caps) - (default_xen_spec_ctrl & SPEC_CTRL_IBRS) ? "IBRS+" : "IBRS-", - !boot_cpu_has(X86_FEATURE_SSBD) ? "" : - (default_xen_spec_ctrl & SPEC_CTRL_SSBD) ? " SSBD+" : " SSBD-", -+ !(caps & ARCH_CAPS_TSX_CTRL) ? "" : -+ (opt_tsx & 1) ? " TSX+" : " TSX-", - opt_ibpb ? " IBPB" : "", - opt_l1d_flush ? " L1D_FLUSH" : "", - opt_md_clear_pv || opt_md_clear_hvm ? " VERW" : ""); -@@ -862,6 +869,7 @@ void __init init_speculation_mitigations(void) - { - enum ind_thunk thunk = THUNK_DEFAULT; - bool use_spec_ctrl = false, ibrs = false, hw_smt_enabled; -+ bool cpu_has_bug_taa; - uint64_t caps = 0; - - if ( boot_cpu_has(X86_FEATURE_ARCH_CAPS) ) -@@ -1086,6 +1094,53 @@ void __init init_speculation_mitigations(void) - "enabled. Mitigations will not be fully effective. Please\n" - "choose an explicit smt=<bool> setting. See XSA-297.\n"); - -+ /* -+ * Vulnerability to TAA is a little complicated to quantify. -+ * -+ * In the pipeline, it is just another way to get speculative access to -+ * stale load port, store buffer or fill buffer data, and therefore can be -+ * considered a superset of MDS (on TSX-capable parts). On parts which -+ * predate MDS_NO, the existing VERW flushing will mitigate this -+ * sidechannel as well. -+ * -+ * On parts which contain MDS_NO, the lack of VERW flushing means that an -+ * attacker can still use TSX to target microarchitectural buffers to leak -+ * secrets. Therefore, we consider TAA to be the set of TSX-capable parts -+ * which have MDS_NO but lack TAA_NO. -+ * -+ * Note: cpu_has_rtm (== hle) could already be hidden by `tsx=0` on the -+ * cmdline. MSR_TSX_CTRL will only appear on TSX-capable parts, so -+ * we check both to spot TSX in a microcode/cmdline independent way. -+ */ -+ cpu_has_bug_taa = -+ (cpu_has_rtm || (caps & ARCH_CAPS_TSX_CTRL)) && -+ (caps & (ARCH_CAPS_MDS_NO | ARCH_CAPS_TAA_NO)) == ARCH_CAPS_MDS_NO; -+ -+ /* -+ * On TAA-affected hardware, disabling TSX is the preferred mitigation, vs -+ * the MDS mitigation of disabling HT and using VERW flushing. -+ * -+ * On CPUs which advertise MDS_NO, VERW has no flushing side effect until -+ * the TSX_CTRL microcode is loaded, despite the MD_CLEAR CPUID bit being -+ * advertised, and there isn't a MD_CLEAR_2 flag to use... -+ * -+ * If we're on affected hardware, able to do something about it (which -+ * implies that VERW now works), no explicit TSX choice and traditional -+ * MDS mitigations (no-SMT, VERW) not obviosuly in use (someone might -+ * plausibly value TSX higher than Hyperthreading...), disable TSX to -+ * mitigate TAA. -+ */ -+ if ( opt_tsx == -1 && cpu_has_bug_taa && (caps & ARCH_CAPS_TSX_CTRL) && -+ ((hw_smt_enabled && opt_smt) || -+ !boot_cpu_has(X86_FEATURE_SC_VERW_IDLE)) ) -+ { -+ setup_clear_cpu_cap(X86_FEATURE_HLE); -+ setup_clear_cpu_cap(X86_FEATURE_RTM); -+ -+ opt_tsx = 0; -+ tsx_init(); -+ } -+ - print_details(thunk, caps); - - /* -diff --git a/xen/arch/x86/tsx.c b/xen/arch/x86/tsx.c -index a8ec2ccc69..2d202a0d4e 100644 ---- a/xen/arch/x86/tsx.c -+++ b/xen/arch/x86/tsx.c -@@ -5,7 +5,8 @@ - * Valid values: - * 1 => Explicit tsx=1 - * 0 => Explicit tsx=0 -- * -1 => Default, implicit tsx=1 -+ * -1 => Default, implicit tsx=1, may change to 0 to mitigate TAA -+ * -3 => Implicit tsx=1 (feed-through from spec-ctrl=0) - * - * This is arranged such that the bottom bit encodes whether TSX is actually - * disabled, while identifying various explicit (>=0) and implicit (<0) -diff --git a/xen/include/asm-x86/msr-index.h b/xen/include/asm-x86/msr-index.h -index d5f3899f73..3971b992d3 100644 ---- a/xen/include/asm-x86/msr-index.h -+++ b/xen/include/asm-x86/msr-index.h -@@ -54,6 +54,7 @@ - #define ARCH_CAPS_MDS_NO (_AC(1, ULL) << 5) - #define ARCH_CAPS_IF_PSCHANGE_MC_NO (_AC(1, ULL) << 6) - #define ARCH_CAPS_TSX_CTRL (_AC(1, ULL) << 7) -+#define ARCH_CAPS_TAA_NO (_AC(1, ULL) << 8) - - #define MSR_FLUSH_CMD 0x0000010b - #define FLUSH_CMD_L1D (_AC(1, ULL) << 0) |