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SUSE:SLE-15-SP1:GA
xen.8389
5afc13ae-5-x86-rename-bits-of-spec_ctrl-infrast...
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File 5afc13ae-5-x86-rename-bits-of-spec_ctrl-infrastructure.patch of Package xen.8389
# Commit d9822b8a38114e96e4516dc998f4055249364d5d # Date 2018-05-16 12:19:10 +0100 # Author Andrew Cooper <andrew.cooper3@citrix.com> # Committer Andrew Cooper <andrew.cooper3@citrix.com> x86/spec_ctrl: Rename bits of infrastructure to avoid NATIVE and VMEXIT In hindsight, using NATIVE and VMEXIT as naming terminology was not clever. A future change wants to split SPEC_CTRL_EXIT_TO_GUEST into PV and HVM specific implementations, and using VMEXIT as a term is completely wrong. Take the opportunity to fix some stale documentation in spec_ctrl_asm.h. The IST helpers were missing from the large comment block, and since SPEC_CTRL_ENTRY_FROM_INTR_IST was introduced, we've gained a new piece of functionality which currently depends on the fine grain control, which exists in lieu of livepatching. Note this in the comment. No functional change. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Reviewed-by: Wei Liu <wei.liu2@citrix.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> --- a/xen/arch/x86/hvm/svm/entry.S +++ b/xen/arch/x86/hvm/svm/entry.S @@ -83,7 +83,7 @@ UNLIKELY_END(svm_trace) mov VCPUMSR_spec_ctrl_raw(%rax), %eax /* WARNING! `ret`, `call *`, `jmp *` not safe beyond this point. */ - SPEC_CTRL_EXIT_TO_GUEST /* Req: a=spec_ctrl %rsp=regs/cpuinfo, Clob: cd */ + SPEC_CTRL_EXIT_TO_HVM /* Req: a=spec_ctrl %rsp=regs/cpuinfo, Clob: cd */ pop %r15 pop %r14 @@ -108,7 +108,7 @@ UNLIKELY_END(svm_trace) GET_CURRENT(bx) - SPEC_CTRL_ENTRY_FROM_VMEXIT /* Req: b=curr %rsp=regs/cpuinfo, Clob: acd */ + SPEC_CTRL_ENTRY_FROM_HVM /* Req: b=curr %rsp=regs/cpuinfo, Clob: acd */ /* WARNING! `ret`, `call *`, `jmp *` not safe before this point. */ mov VCPU_svm_vmcb(%rbx),%rcx --- a/xen/arch/x86/hvm/vmx/entry.S +++ b/xen/arch/x86/hvm/vmx/entry.S @@ -38,7 +38,7 @@ ENTRY(vmx_asm_vmexit_handler) movb $1,VCPU_vmx_launched(%rbx) mov %rax,VCPU_hvm_guest_cr2(%rbx) - SPEC_CTRL_ENTRY_FROM_VMEXIT /* Req: b=curr %rsp=regs/cpuinfo, Clob: acd */ + SPEC_CTRL_ENTRY_FROM_HVM /* Req: b=curr %rsp=regs/cpuinfo, Clob: acd */ /* WARNING! `ret`, `call *`, `jmp *` not safe before this point. */ mov %rsp,%rdi @@ -76,7 +76,7 @@ UNLIKELY_END(realmode) mov VCPUMSR_spec_ctrl_raw(%rax), %eax /* WARNING! `ret`, `call *`, `jmp *` not safe beyond this point. */ - SPEC_CTRL_EXIT_TO_GUEST /* Req: a=spec_ctrl %rsp=regs/cpuinfo, Clob: cd */ + SPEC_CTRL_EXIT_TO_HVM /* Req: a=spec_ctrl %rsp=regs/cpuinfo, Clob: cd */ mov VCPU_hvm_guest_cr2(%rbx),%rax --- a/xen/arch/x86/spec_ctrl.c +++ b/xen/arch/x86/spec_ctrl.c @@ -35,8 +35,8 @@ static enum ind_thunk { THUNK_JMP, } opt_thunk __initdata = THUNK_DEFAULT; static int8_t __initdata opt_ibrs = -1; -static bool __initdata opt_rsb_native = true; -static bool __initdata opt_rsb_vmexit = true; +static bool __initdata opt_rsb_pv = true; +static bool __initdata opt_rsb_hvm = true; bool __read_mostly opt_ibpb = true; uint8_t __read_mostly default_xen_spec_ctrl; uint8_t __read_mostly default_spec_ctrl_flags; @@ -69,9 +69,9 @@ static int __init parse_bti(const char * else if ( (val = parse_boolean("ibpb", s, ss)) >= 0 ) opt_ibpb = val; else if ( (val = parse_boolean("rsb_native", s, ss)) >= 0 ) - opt_rsb_native = val; + opt_rsb_pv = val; else if ( (val = parse_boolean("rsb_vmexit", s, ss)) >= 0 ) - opt_rsb_vmexit = val; + opt_rsb_hvm = val; else rc = -EINVAL; @@ -116,8 +116,8 @@ static void __init print_details(enum in default_xen_spec_ctrl & SPEC_CTRL_IBRS ? " IBRS+" : " IBRS-" : "", opt_ibpb ? " IBPB" : "", - boot_cpu_has(X86_FEATURE_RSB_NATIVE) ? " RSB_NATIVE" : "", - boot_cpu_has(X86_FEATURE_RSB_VMEXIT) ? " RSB_VMEXIT" : ""); + boot_cpu_has(X86_FEATURE_SC_RSB_PV) ? " RSB_NATIVE" : "", + boot_cpu_has(X86_FEATURE_SC_RSB_HVM) ? " RSB_VMEXIT" : ""); printk("XPTI: %s\n", boot_cpu_has(X86_FEATURE_NO_XPTI) ? "disabled" : "enabled"); @@ -307,9 +307,9 @@ void __init init_speculation_mitigations * If a processors speculates to 32bit PV guest kernel mappings, it is * speculating in 64bit supervisor mode, and can leak data. */ - if ( opt_rsb_native ) + if ( opt_rsb_pv ) { - setup_force_cpu_cap(X86_FEATURE_RSB_NATIVE); + setup_force_cpu_cap(X86_FEATURE_SC_RSB_PV); default_spec_ctrl_flags |= SCF_ist_rsb; } @@ -317,8 +317,8 @@ void __init init_speculation_mitigations * HVM guests can always poison the RSB to point at Xen supervisor * mappings. */ - if ( opt_rsb_vmexit ) - setup_force_cpu_cap(X86_FEATURE_RSB_VMEXIT); + if ( opt_rsb_hvm ) + setup_force_cpu_cap(X86_FEATURE_SC_RSB_HVM); /* Check we have hardware IBPB support before using it... */ if ( !boot_cpu_has(X86_FEATURE_IBRSB) && !boot_cpu_has(X86_FEATURE_IBPB) ) --- a/xen/arch/x86/x86_64/compat/entry.S +++ b/xen/arch/x86/x86_64/compat/entry.S @@ -166,7 +166,7 @@ ENTRY(compat_restore_all_guest) mov VCPUMSR_spec_ctrl_raw(%rax), %eax /* WARNING! `ret`, `call *`, `jmp *` not safe beyond this point. */ - SPEC_CTRL_EXIT_TO_GUEST /* Req: a=spec_ctrl %rsp=regs/cpuinfo, Clob: cd */ + SPEC_CTRL_EXIT_TO_PV /* Req: a=spec_ctrl %rsp=regs/cpuinfo, Clob: cd */ RESTORE_ALL adj=8 compat=1 .Lft0: iretq --- a/xen/arch/x86/x86_64/entry.S +++ b/xen/arch/x86/x86_64/entry.S @@ -196,7 +196,7 @@ restore_all_guest: mov %r15d, %eax /* WARNING! `ret`, `call *`, `jmp *` not safe beyond this point. */ - SPEC_CTRL_EXIT_TO_GUEST /* Req: a=spec_ctrl %rsp=regs/cpuinfo, Clob: cd */ + SPEC_CTRL_EXIT_TO_PV /* Req: a=spec_ctrl %rsp=regs/cpuinfo, Clob: cd */ RESTORE_ALL testw $TRAP_syscall,4(%rsp) --- a/xen/include/asm-x86/cpufeatures.h +++ b/xen/include/asm-x86/cpufeatures.h @@ -27,6 +27,6 @@ XEN_CPUFEATURE(IND_THUNK_LFENCE,(FSCAPIN XEN_CPUFEATURE(IND_THUNK_JMP, (FSCAPINTS+0)*32+14) /* Use IND_THUNK_JMP */ XEN_CPUFEATURE(XEN_IBPB, (FSCAPINTS+0)*32+15) /* IBRSB || IBPB */ XEN_CPUFEATURE(SC_MSR, (FSCAPINTS+0)*32+16) /* MSR_SPEC_CTRL used by Xen */ -XEN_CPUFEATURE(RSB_NATIVE, (FSCAPINTS+0)*32+18) /* RSB overwrite needed for native */ -XEN_CPUFEATURE(RSB_VMEXIT, (FSCAPINTS+0)*32+19) /* RSB overwrite needed for vmexit */ +XEN_CPUFEATURE(SC_RSB_PV, (FSCAPINTS+0)*32+18) /* RSB overwrite needed for PV */ +XEN_CPUFEATURE(SC_RSB_HVM, (FSCAPINTS+0)*32+19) /* RSB overwrite needed for HVM */ XEN_CPUFEATURE(NO_XPTI, (FSCAPINTS+0)*32+20) /* XPTI mitigation not in use */ --- a/xen/include/asm-x86/spec_ctrl_asm.h +++ b/xen/include/asm-x86/spec_ctrl_asm.h @@ -72,11 +72,14 @@ * * The following ASM fragments implement this algorithm. See their local * comments for further details. - * - SPEC_CTRL_ENTRY_FROM_VMEXIT + * - SPEC_CTRL_ENTRY_FROM_HVM * - SPEC_CTRL_ENTRY_FROM_PV * - SPEC_CTRL_ENTRY_FROM_INTR + * - SPEC_CTRL_ENTRY_FROM_INTR_IST + * - SPEC_CTRL_EXIT_TO_XEN_IST * - SPEC_CTRL_EXIT_TO_XEN - * - SPEC_CTRL_EXIT_TO_GUEST + * - SPEC_CTRL_EXIT_TO_PV + * - SPEC_CTRL_EXIT_TO_HVM */ .macro DO_OVERWRITE_RSB tmp=rax @@ -117,7 +120,7 @@ mov %\tmp, %rsp /* Restore old %rsp */ .endm -.macro DO_SPEC_CTRL_ENTRY_FROM_VMEXIT +.macro DO_SPEC_CTRL_ENTRY_FROM_HVM /* * Requires %rbx=current, %rsp=regs/cpuinfo * Clobbers %rax, %rcx, %rdx @@ -217,23 +220,23 @@ .endm /* Use after a VMEXIT from an HVM guest. */ -#define SPEC_CTRL_ENTRY_FROM_VMEXIT \ +#define SPEC_CTRL_ENTRY_FROM_HVM \ ALTERNATIVE __stringify(ASM_NOP40), \ - DO_OVERWRITE_RSB, X86_FEATURE_RSB_VMEXIT; \ + DO_OVERWRITE_RSB, X86_FEATURE_SC_RSB_HVM; \ ALTERNATIVE __stringify(ASM_NOP36), \ - DO_SPEC_CTRL_ENTRY_FROM_VMEXIT, X86_FEATURE_SC_MSR + DO_SPEC_CTRL_ENTRY_FROM_HVM, X86_FEATURE_SC_MSR /* Use after an entry from PV context (syscall/sysenter/int80/int82/etc). */ #define SPEC_CTRL_ENTRY_FROM_PV \ ALTERNATIVE __stringify(ASM_NOP40), \ - DO_OVERWRITE_RSB, X86_FEATURE_RSB_NATIVE; \ + DO_OVERWRITE_RSB, X86_FEATURE_SC_RSB_PV; \ ALTERNATIVE __stringify(ASM_NOP25), \ __stringify(DO_SPEC_CTRL_ENTRY maybexen=0), X86_FEATURE_SC_MSR /* Use in interrupt/exception context. May interrupt Xen or PV context. */ #define SPEC_CTRL_ENTRY_FROM_INTR \ ALTERNATIVE __stringify(ASM_NOP40), \ - DO_OVERWRITE_RSB, X86_FEATURE_RSB_NATIVE; \ + DO_OVERWRITE_RSB, X86_FEATURE_SC_RSB_PV; \ ALTERNATIVE __stringify(ASM_NOP33), \ __stringify(DO_SPEC_CTRL_ENTRY maybexen=1), X86_FEATURE_SC_MSR @@ -242,12 +245,22 @@ ALTERNATIVE __stringify(ASM_NOP17), \ DO_SPEC_CTRL_EXIT_TO_XEN, X86_FEATURE_SC_MSR -/* Use when exiting to guest context. */ -#define SPEC_CTRL_EXIT_TO_GUEST \ +/* Use when exiting to PV guest context. */ +#define SPEC_CTRL_EXIT_TO_PV \ ALTERNATIVE __stringify(ASM_NOP24), \ DO_SPEC_CTRL_EXIT_TO_GUEST, X86_FEATURE_SC_MSR -/* TODO: Drop these when the alternatives infrastructure is NMI/#MC safe. */ +/* Use when exiting to HVM guest context. */ +#define SPEC_CTRL_EXIT_TO_HVM \ + ALTERNATIVE __stringify(ASM_NOP24), \ + DO_SPEC_CTRL_EXIT_TO_GUEST, X86_FEATURE_SC_MSR + +/* + * Use in IST interrupt/exception context. May interrupt Xen or PV context. + * Fine grain control of SCF_ist_wrmsr is needed for safety in the S3 resume + * path to avoid using MSR_SPEC_CTRL before the microcode introducing it has + * been reloaded. + */ .macro SPEC_CTRL_ENTRY_FROM_INTR_IST /* * Requires %rsp=regs, %r14=stack_end @@ -294,6 +307,7 @@ UNLIKELY_DISPATCH_LABEL(\@_serialise): UNLIKELY_END(\@_serialise) .endm +/* Use when exiting to Xen in IST context. */ .macro SPEC_CTRL_EXIT_TO_XEN_IST /* * Requires %rbx=stack_end
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