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SUSE:SLE-12-SP1:GA
xen.8005
5b02c786-x86-Intel-mitigations-for-GPZ-SP4.patch
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File 5b02c786-x86-Intel-mitigations-for-GPZ-SP4.patch of Package xen.8005
# Commit 9df52a25e0e95a0b9971aa2fc26c5c6a5cbdf4ef # Date 2018-05-21 14:20:06 +0100 # Author Andrew Cooper <andrew.cooper3@citrix.com> # Committer Andrew Cooper <andrew.cooper3@citrix.com> x86/Intel: Mitigations for GPZ SP4 - Speculative Store Bypass To combat GPZ SP4 "Speculative Store Bypass", Intel have extended their speculative sidechannel mitigations specification as follows: * A feature bit to indicate that Speculative Store Bypass Disable is supported. * A new bit in MSR_SPEC_CTRL which, when set, disables memory disambiguation in the pipeline. * A new bit in MSR_ARCH_CAPABILITIES, which will be set in future hardware, indicating that the hardware is not susceptible to Speculative Store Bypass sidechannels. For contemporary processors, this interface will be implemented via a microcode update. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> --- a/docs/misc/xen-command-line.markdown +++ b/docs/misc/xen-command-line.markdown @@ -348,9 +348,10 @@ accounting for hardware capabilities as Currently accepted: -The Speculation Control hardware features `ibrsb`, `stibp`, `ibpb` are used by -default if avaiable. They can be ignored, e.g. `no-ibrsb`, at which point Xen -won't use them itself, and won't offer them to guests. +The Speculation Control hardware features `ibrsb`, `stibp`, `ibpb`, `ssbd` are +used by default if available and applicable. They can be ignored, +e.g. `no-ibrsb`, at which point Xen won't use them itself, and won't offer +them to guests. ### cpuid\_mask\_cpu (AMD only) > `= fam_0f_rev_c | fam_0f_rev_d | fam_0f_rev_e | fam_0f_rev_f | fam_0f_rev_g | fam_10_rev_b | fam_10_rev_c | fam_11_rev_b` @@ -1010,7 +1011,7 @@ protect itself, and Xen's ability to vir respectively. * `msr-sc=` offers control over Xen's support for manipulating MSR\_SPEC\_CTRL on entry and exit. These blocks are necessary to virtualise support for - guests and if disabled, guests will be unable to use IBRS/STIBP/etc. + guests and if disabled, guests will be unable to use IBRS/STIBP/SSBD/etc. * `rsb=` offers control over whether to overwrite the Return Stack Buffer / Return Address Stack on entry to Xen. @@ -1032,7 +1033,8 @@ prediction barriers on vcpu context swit On hardware supporting SSBD (Speculative Store Bypass Disable), the `ssbd=` option can be used to force or prevent Xen using the feature itself. On AMD hardware, this is a global option applied at boot, and not virtualised for -guest use. +guest use. On Intel hardware, the feature is virtualised for guests, +independently of Xen's choice of setting. ### sync\_console > `= <boolean>` --- a/tools/libxl/libxl_cpuid.c +++ b/tools/libxl/libxl_cpuid.c @@ -156,6 +156,7 @@ int libxl_cpuid_parse_config(libxl_cpuid {"ibrsb", 0x00000007, 0, CPUID_REG_EDX, 26, 1}, {"stibp", 0x00000007, 0, CPUID_REG_EDX, 27, 1}, {"arch-caps", 0x00000007, 0, CPUID_REG_EDX, 29, 1}, + {"ssbd", 0x00000007, 0, CPUID_REG_EDX, 31, 1}, {"topoext", 0x80000001, NA, CPUID_REG_ECX, 22, 1}, {"tbm", 0x80000001, NA, CPUID_REG_ECX, 21, 1}, {"nodeid", 0x80000001, NA, CPUID_REG_ECX, 19, 1}, --- a/xen/arch/x86/hvm/hvm.c +++ b/xen/arch/x86/hvm/hvm.c @@ -59,6 +59,7 @@ #include <asm/hvm/nestedhvm.h> #include <asm/mtrr.h> #include <asm/apic.h> +#include <asm/spec_ctrl.h> #include <public/sched.h> #include <public/hvm/ioreq.h> #include <public/version.h> @@ -3200,7 +3201,8 @@ void hvm_cpuid(unsigned int input, unsig if ( count == 0 ) { if ( !opt_msr_sc_hvm ) - *edx &= ~cpufeat_mask(X86_FEATURE_IBRSB); + *edx &= ~(cpufeat_mask(X86_FEATURE_IBRSB) | + cpufeat_mask(X86_FEATURE_SSBD)); /* * Override STIBP to match IBRS. Guests can safely use STIBP --- a/xen/arch/x86/setup.c +++ b/xen/arch/x86/setup.c @@ -125,6 +125,11 @@ static int __init parse_xen_cpuid(const if ( !val ) setup_clear_cpu_cap(X86_FEATURE_STIBP); } + else if ( (val = parse_boolean("ssbd", s, ss)) >= 0 ) + { + if ( !val ) + setup_clear_cpu_cap(X86_FEATURE_SSBD); + } else rc = -EINVAL; --- a/xen/arch/x86/spec_ctrl.c +++ b/xen/arch/x86/spec_ctrl.c @@ -159,9 +159,10 @@ static void __init print_details(enum in printk("Speculative mitigation facilities:\n"); /* Hardware features which pertain to speculative mitigations. */ - printk(" Hardware features:%s%s%s%s%s%s\n", + printk(" Hardware features:%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_SSBD)) ? " SSBD" : "", (e8b & cpufeat_mask(X86_FEATURE_IBPB)) ? " IBPB" : "", (caps & ARCH_CAPABILITIES_IBRS_ALL) ? " IBRS_ALL" : "", (caps & ARCH_CAPABILITIES_RDCL_NO) ? " RDCL_NO" : "", @@ -173,11 +174,14 @@ static void __init print_details(enum in #endif /* Settings for Xen's protection, irrespective of guests. */ - printk(" Xen settings: BTI-Thunk %s, SPEC_CTRL: %s, Other:%s\n", + printk(" Xen settings: BTI-Thunk %s, SPEC_CTRL: %s%s, Other:%s\n", thunk == THUNK_NONE ? "N/A" : thunk == THUNK_RETPOLINE ? "RETPOLINE" : "?", default_xen_spec_ctrl < 0 ? "" : default_xen_spec_ctrl & SPEC_CTRL_IBRS ? " IBRS+" : " IBRS-", + default_xen_spec_ctrl < 0 || !boot_cpu_has(X86_FEATURE_SSBD) + ? "" : + (default_xen_spec_ctrl & SPEC_CTRL_SSBD) ? " SSBD+" : " SSBD-", opt_ibpb ? " IBPB" : ""); printk(" Support for VMs: PV:%s%s%s, HVM:%s%s%s\n", @@ -223,6 +227,10 @@ void __init init_speculation_mitigations if ( boot_cpu_has(X86_FEATURE_IBRSB) ) default_xen_spec_ctrl = ibrs ? SPEC_CTRL_IBRS : 0; + /* If we have SSBD available, see whether we should use it. */ + if ( boot_cpu_has(X86_FEATURE_SSBD) && opt_ssbd ) + default_xen_spec_ctrl |= SPEC_CTRL_SSBD; + /* * PV guests can poison the RSB to any virtual address from which * they can execute a call instruction. This is necessarily outside --- a/xen/arch/x86/traps.c +++ b/xen/arch/x86/traps.c @@ -72,6 +72,7 @@ #include <asm/apic.h> #include <asm/mc146818rtc.h> #include <asm/hpet.h> +#include <asm/spec_ctrl.h> #include <public/arch-x86/cpuid.h> #include <xsm/xsm.h> @@ -784,7 +785,8 @@ void pv_cpuid(struct cpu_user_regs *regs if ( regs->_ecx == 0 ) { if ( !opt_msr_sc_pv ) - d &= ~cpufeat_mask(X86_FEATURE_IBRSB); + d &= ~(cpufeat_mask(X86_FEATURE_IBRSB) | + cpufeat_mask(X86_FEATURE_SSBD)); /* * Override STIBP to match IBRS. Guests can safely use STIBP @@ -871,7 +873,8 @@ void pv_cpuid(struct cpu_user_regs *regs cpufeat_mask(X86_FEATURE_FSGSBASE)); if ( opt_msr_sc_pv ) - d &= cpufeat_mask(X86_FEATURE_IBRSB); + d &= cpufeat_mask(X86_FEATURE_IBRSB) | + cpufeat_mask(X86_FEATURE_SSBD); else d = 0; --- a/xen/include/asm-x86/cpufeature.h +++ b/xen/include/asm-x86/cpufeature.h @@ -161,6 +161,7 @@ #define X86_FEATURE_IBRSB (9*32+26) /* IBRS and IBPB support (used by Intel) */ #define X86_FEATURE_STIBP (9*32+27) /* STIBP */ #define X86_FEATURE_ARCH_CAPS (9*32+29) /* IA32_ARCH_CAPABILITIES MSR */ +#define X86_FEATURE_SSBD (9*32+31) /* MSR_SPEC_CTRL.SSBD available */ #define cpu_has(c, bit) test_bit(bit, (c)->x86_capability) #define boot_cpu_has(bit) test_bit(bit, boot_cpu_data.x86_capability) --- a/xen/include/asm-x86/msr-index.h +++ b/xen/include/asm-x86/msr-index.h @@ -35,6 +35,7 @@ #define MSR_SPEC_CTRL 0x00000048 #define SPEC_CTRL_IBRS (_AC(1, ULL) << 0) #define SPEC_CTRL_STIBP (_AC(1, ULL) << 1) +#define SPEC_CTRL_SSBD (_AC(1, ULL) << 2) #define MSR_PRED_CMD 0x00000049 #define PRED_CMD_IBPB (_AC(1, ULL) << 0)
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