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SUSE:SLE-15-SP1:Update
xen.7985
5aec744a-3-x86-xpti-per-domain-flag.patch
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File 5aec744a-3-x86-xpti-per-domain-flag.patch of Package xen.7985
From 0d3e7f0b6bf01fbd6250fd3408a22fead1601bf0 Mon Sep 17 00:00:00 2001 From: Juergen Gross <jgross@suse.com> Date: Thu, 26 Apr 2018 13:33:12 +0200 Subject: [PATCH] xen/x86: support per-domain flag for xpti Instead of switching XPTI globally on or off add a per-domain flag for that purpose. This allows to modify the xpti boot parameter to support running dom0 without Meltdown mitigations. Using "xpti=no-dom0" as boot parameter will achieve that. Move the xpti boot parameter handling to xen/arch/x86/pv/domain.c as it is pv-domain specific. Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> --- docs/misc/xen-command-line.markdown | 14 ++++++- xen/arch/x86/mm.c | 17 ++++++++- xen/arch/x86/pv/dom0_build.c | 1 + xen/arch/x86/pv/domain.c | 6 +++ xen/arch/x86/setup.c | 19 ---------- xen/arch/x86/smpboot.c | 4 +- xen/arch/x86/spec_ctrl.c | 75 ++++++++++++++++++++++++++++++++++++- xen/include/asm-x86/current.h | 3 +- xen/include/asm-x86/domain.h | 3 ++ xen/include/asm-x86/flushtlb.h | 2 +- xen/include/asm-x86/spec_ctrl.h | 4 ++ 11 files changed, 119 insertions(+), 29 deletions(-) --- a/docs/misc/xen-command-line.markdown +++ b/docs/misc/xen-command-line.markdown @@ -1972,14 +1972,24 @@ clustered mode. The default, given no h mode. ### xpti -> `= <boolean>` +> `= List of [ default | <boolean> | dom0=<bool> | domu=<bool> ]` -> Default: `false` on AMD hardware +> Default: `false` on hardware not to be vulnerable to Meltdown (e.g. AMD) > Default: `true` everywhere else Override default selection of whether to isolate 64-bit PV guest page tables. +`true` activates page table isolation even on hardware not vulnerable by +Meltdown for all domains. + +`false` deactivates page table isolation on all systems for all domains. + +`default` sets the default behaviour. + +With `dom0` and `domu` it is possible to control page table isolation +for dom0 or guest domains only. + ### xsave > `= <boolean>` --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -508,8 +508,21 @@ void make_cr3(struct vcpu *v, mfn_t mfn) void write_ptbase(struct vcpu *v) { - get_cpu_info()->root_pgt_changed = true; - switch_cr3(v->arch.cr3); + struct cpu_info *cpu_info = get_cpu_info(); + + if ( is_pv_vcpu(v) && v->domain->arch.pv_domain.xpti ) + { + cpu_info->root_pgt_changed = true; + cpu_info->pv_cr3 = __pa(this_cpu(root_pgt)); + switch_cr3(v->arch.cr3); + } + else + { + /* Make sure to clear xen_cr3 before pv_cr3; switch_cr3() serializes. */ + cpu_info->xen_cr3 = 0; + switch_cr3(v->arch.cr3); + cpu_info->pv_cr3 = 0; + } } /* --- a/xen/arch/x86/pv/dom0_build.c +++ b/xen/arch/x86/pv/dom0_build.c @@ -388,6 +388,7 @@ int __init dom0_construct_pv(struct doma if ( compat32 ) { d->arch.is_32bit_pv = d->arch.has_32bit_shinfo = 1; + d->arch.pv_domain.xpti = false; v->vcpu_info = (void *)&d->shared_info->compat.vcpu_info[0]; if ( setup_compat_arg_xlat(v) != 0 ) BUG(); --- a/xen/arch/x86/pv/domain.c +++ b/xen/arch/x86/pv/domain.c @@ -9,6 +9,7 @@ #include <xen/lib.h> #include <xen/sched.h> +#include <asm/spec_ctrl.h> #include <asm/pv/domain.h> /* Override macros from asm/page.h to make them work with mfn_t */ @@ -81,6 +82,8 @@ int switch_compat(struct domain *d) d->arch.x87_fip_width = 4; + d->arch.pv_domain.xpti = false; + return 0; undo_and_fail: @@ -212,6 +215,9 @@ int pv_domain_initialise(struct domain * /* 64-bit PV guest by default. */ d->arch.is_32bit_pv = d->arch.has_32bit_shinfo = 0; + d->arch.pv_domain.xpti = opt_xpti & (is_hardware_domain(d) + ? OPT_XPTI_DOM0 : OPT_XPTI_DOMU); + return 0; fail: --- a/xen/arch/x86/setup.c +++ b/xen/arch/x86/setup.c @@ -169,9 +169,6 @@ static int __init parse_smap_param(const } custom_param("smap", parse_smap_param); -static int8_t __initdata opt_xpti = -1; -boolean_param("xpti", opt_xpti); - bool __read_mostly acpi_disabled; bool __initdata acpi_force; static char __initdata acpi_param[10] = ""; @@ -1539,22 +1536,6 @@ void __init noreturn __start_xen(unsigne cr4_pv32_mask = mmu_cr4_features & XEN_CR4_PV32_BITS; - if ( opt_xpti < 0 ) - { - uint64_t caps = 0; - - if ( boot_cpu_data.x86_vendor == X86_VENDOR_AMD ) - caps = ARCH_CAPABILITIES_RDCL_NO; - else if ( boot_cpu_has(X86_FEATURE_ARCH_CAPS) ) - rdmsrl(MSR_ARCH_CAPABILITIES, caps); - - opt_xpti = !(caps & ARCH_CAPABILITIES_RDCL_NO); - } - if ( opt_xpti ) - setup_clear_cpu_cap(X86_FEATURE_NO_XPTI); - else - setup_force_cpu_cap(X86_FEATURE_NO_XPTI); - if ( cpu_has_fsgsbase ) set_in_cr4(X86_CR4_FSGSBASE); --- a/xen/arch/x86/smpboot.c +++ b/xen/arch/x86/smpboot.c @@ -331,7 +331,7 @@ void start_secondary(void *unused) spin_debug_disable(); get_cpu_info()->xen_cr3 = 0; - get_cpu_info()->pv_cr3 = this_cpu(root_pgt) ? __pa(this_cpu(root_pgt)) : 0; + get_cpu_info()->pv_cr3 = 0; load_system_tables(); @@ -1056,7 +1056,7 @@ void __init smp_prepare_cpus(unsigned in panic("Error %d setting up PV root page table\n", rc); if ( per_cpu(root_pgt, 0) ) { - get_cpu_info()->pv_cr3 = __pa(per_cpu(root_pgt, 0)); + get_cpu_info()->pv_cr3 = 0; /* * All entry points which may need to switch page tables have to start --- a/xen/arch/x86/spec_ctrl.c +++ b/xen/arch/x86/spec_ctrl.c @@ -225,8 +225,9 @@ static void __init print_details(enum in boot_cpu_has(X86_FEATURE_SC_MSR_HVM) ? " MSR_SPEC_CTRL" : "", boot_cpu_has(X86_FEATURE_SC_RSB_HVM) ? " RSB" : ""); - printk("XPTI: %s\n", - boot_cpu_has(X86_FEATURE_NO_XPTI) ? "disabled" : "enabled"); + printk(" XPTI (64-bit PV only): Dom0 %s, DomU %s\n", + opt_xpti & OPT_XPTI_DOM0 ? "enabled" : "disabled", + opt_xpti & OPT_XPTI_DOMU ? "enabled" : "disabled"); } /* Calculate whether Retpoline is known-safe on this CPU. */ @@ -312,6 +313,70 @@ static bool __init retpoline_safe(uint64 } } +#define OPT_XPTI_DEFAULT 0xff +uint8_t __read_mostly opt_xpti = OPT_XPTI_DEFAULT; + +static __init void xpti_init_default(bool force) +{ + uint64_t caps = 0; + + if ( !force && (opt_xpti != OPT_XPTI_DEFAULT) ) + return; + + if ( boot_cpu_data.x86_vendor == X86_VENDOR_AMD ) + caps = ARCH_CAPABILITIES_RDCL_NO; + else if ( boot_cpu_has(X86_FEATURE_ARCH_CAPS) ) + rdmsrl(MSR_ARCH_CAPABILITIES, caps); + + if ( caps & ARCH_CAPABILITIES_RDCL_NO ) + opt_xpti = 0; + else + opt_xpti = OPT_XPTI_DOM0 | OPT_XPTI_DOMU; +} + +static __init int parse_xpti(const char *s) +{ + const char *ss; + int val, rc = 0; + + xpti_init_default(false); + + do { + ss = strchr(s, ','); + if ( !ss ) + ss = strchr(s, '\0'); + + switch ( parse_bool(s, ss) ) + { + case 0: + opt_xpti = 0; + break; + + case 1: + opt_xpti = OPT_XPTI_DOM0 | OPT_XPTI_DOMU; + break; + + default: + if ( !strcmp(s, "default") ) + xpti_init_default(true); + else if ( (val = parse_boolean("dom0", s, ss)) >= 0 ) + opt_xpti = (opt_xpti & ~OPT_XPTI_DOM0) | + (val ? OPT_XPTI_DOM0 : 0); + else if ( (val = parse_boolean("domu", s, ss)) >= 0 ) + opt_xpti = (opt_xpti & ~OPT_XPTI_DOMU) | + (val ? OPT_XPTI_DOMU : 0); + else + rc = -EINVAL; + break; + } + + s = ss + 1; + } while ( *ss ); + + return rc; +} +custom_param("xpti", parse_xpti); + void __init init_speculation_mitigations(void) { enum ind_thunk thunk = THUNK_DEFAULT; @@ -449,6 +514,12 @@ void __init init_speculation_mitigations if ( default_xen_spec_ctrl ) setup_force_cpu_cap(X86_FEATURE_SC_MSR_IDLE); + xpti_init_default(false); + if ( opt_xpti == 0 ) + setup_force_cpu_cap(X86_FEATURE_NO_XPTI); + else + setup_clear_cpu_cap(X86_FEATURE_NO_XPTI); + print_details(thunk, caps); /* --- a/xen/include/asm-x86/current.h +++ b/xen/include/asm-x86/current.h @@ -44,7 +44,8 @@ struct cpu_info { /* * Of the two following fields the latter is being set to the CR3 value * to be used on the given pCPU for loading whenever 64-bit PV guest - * context is being entered. The value never changes once set. + * context is being entered. A value of zero indicates no setting of CR3 + * is to be performed. * The former is the value to restore when re-entering Xen, if any. IOW * its value being zero means there's nothing to restore. However, its * value can also be negative, indicating to the exit-to-Xen code that --- a/xen/include/asm-x86/domain.h +++ b/xen/include/asm-x86/domain.h @@ -253,6 +253,9 @@ struct pv_domain atomic_t nr_l4_pages; + /* XPTI active? */ + bool xpti; + /* map_domain_page() mapping cache. */ struct mapcache_domain mapcache; --- a/xen/include/asm-x86/flushtlb.h +++ b/xen/include/asm-x86/flushtlb.h @@ -136,7 +136,7 @@ void flush_area_mask(const cpumask_t *, #define flush_root_pgtbl_domain(d) \ { \ - if ( !cpu_has_no_xpti && is_pv_domain(d) && !is_pv_32bit_domain(d) ) \ + if ( is_pv_domain(d) && (d)->arch.pv_domain.xpti ) \ flush_mask((d)->domain_dirty_cpumask, FLUSH_ROOT_PGTBL); \ } --- a/xen/include/asm-x86/spec_ctrl.h +++ b/xen/include/asm-x86/spec_ctrl.h @@ -32,6 +32,10 @@ extern bool bsp_delay_spec_ctrl; extern uint8_t default_xen_spec_ctrl; extern uint8_t default_spec_ctrl_flags; +extern uint8_t opt_xpti; +#define OPT_XPTI_DOM0 0x01 +#define OPT_XPTI_DOMU 0x02 + static inline void init_shadow_spec_ctrl_state(void) { struct cpu_info *info = get_cpu_info();
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