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openSUSE:Step:15-SP4
xen.32200
xsa435-0-54.patch
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File xsa435-0-54.patch of Package xen.32200
From: Andrew Cooper <andrew.cooper3@citrix.com> Origin: https://github.com/xenserver/xen.pg/blob/XS-8.3.x/patches/max-featureset-compat.patch --- a/tools/libxc/xc_cpuid_x86.c +++ b/tools/libxc/xc_cpuid_x86.c @@ -43,6 +43,28 @@ enum { #define DEF_MAX_INTELEXT 0x80000008u #define DEF_MAX_AMDEXT 0x8000001cu +enum vendor { + VENDOR_UNKNOWN, + VENDOR_INTEL, + VENDOR_AMD, +}; + +static enum vendor lookup_vendor(unsigned int ebx, unsigned int ecx, + unsigned int edx) +{ + if ( ebx == 0x756e6547U && /* "GenuineIntel" */ + ecx == 0x6c65746eU && + edx == 0x49656e69U ) + return VENDOR_INTEL; + + if ( ebx == 0x68747541U && /* "AuthenticAMD" */ + ecx == 0x444d4163U && + edx == 0x69746e65U ) + return VENDOR_AMD; + + return VENDOR_UNKNOWN; +} + int xc_get_cpu_levelling_caps(xc_interface *xch, uint32_t *caps) { DECLARE_SYSCTL; @@ -57,8 +79,8 @@ int xc_get_cpu_levelling_caps(xc_interfa return ret; } -int xc_get_cpu_featureset(xc_interface *xch, uint32_t index, - uint32_t *nr_features, uint32_t *featureset) +static int xc_get_cpu_featureset_(xc_interface *xch, uint32_t index, + uint32_t *nr_features, uint32_t *featureset) { DECLARE_SYSCTL; DECLARE_HYPERCALL_BOUNCE(featureset, @@ -84,6 +106,127 @@ int xc_get_cpu_featureset(xc_interface * return ret; } +int xc_get_cpu_featureset(xc_interface *xch, uint32_t index, + uint32_t *nr, uint32_t *fs) +{ + uint32_t raw_fs[FEATURESET_NR_ENTRIES] = {}, raw_nr = ARRAY_SIZE(raw_fs); + uint32_t host_fs[FEATURESET_NR_ENTRIES] = {}, host_nr = ARRAY_SIZE(host_fs); + unsigned int vendor; + int ret; + + if ( index != XEN_SYSCTL_cpu_featureset_pv_max && + index != XEN_SYSCTL_cpu_featureset_hvm_max ) + return xc_get_cpu_featureset_(xch, index, nr, fs); + + /* + * Fake up a *_max featureset. Obtain the raw, host, and pv/hvm default. + * + * This is used by xenopsd to pass to the toolstack of the incoming + * domain, to allow it to establish migration safety. + */ + ret = xc_get_cpu_featureset_( + xch, XEN_SYSCTL_cpu_featureset_raw, &raw_nr, raw_fs); + if ( ret && errno != ENOBUFS ) + return ret; + + ret = xc_get_cpu_featureset_( + xch, XEN_SYSCTL_cpu_featureset_host, &host_nr, host_fs); + if ( ret && errno != ENOBUFS ) + return ret; + + ret = xc_get_cpu_featureset_(xch, index, nr, fs); + if ( ret ) + return ret; + + /* + * Advertise HTT, x2APIC and CMP_LEGACY. They all impact topology, + * unconditionally leak into PV guests, and are fully emulated for HVM. + */ + set_bit(X86_FEATURE_HTT, fs); + set_bit(X86_FEATURE_X2APIC, fs); + set_bit(X86_FEATURE_CMP_LEGACY, fs); + + /* + * Feed HLE/RTM in from the host policy. We can safely migrate in VMs + * which saw HLE/RTM, even if the RTM is disabled for errata/security + * reasons. + */ + clear_bit(X86_FEATURE_HLE, fs); + if ( test_bit(X86_FEATURE_HLE, host_fs) ) + set_bit(X86_FEATURE_HLE, fs); + + clear_bit(X86_FEATURE_RTM, fs); + if ( test_bit(X86_FEATURE_RTM, host_fs) ) + set_bit(X86_FEATURE_RTM, fs); + + /* + * The Gather Data Sampling microcode mitigation (August 2023) has an + * adverse performance impact on the CLWB instruction on SKX/CLX/CPX. + * + * We hid CLWB in the host policy to stop Xen using it, but VMs which + * have previously seen the CLWB feature can safely run on this CPU. + */ + if ( test_bit(X86_FEATURE_CLWB, raw_fs) && + !test_bit(X86_FEATURE_CLWB, host_fs) ) + set_bit(X86_FEATURE_CLWB, fs); + + /* if ( index == XEN_SYSCTL_cpu_featureset_hvm_max ) */ + { + struct cpuid_leaf l; + + cpuid_leaf(0, &l); + vendor = lookup_vendor(l.b, l.c, l.d); + + /* + * MPX has been removed from newer Intel hardware. Therefore, we hide + * it by default, but can still accept any VMs which saw it, if + * hardware is MPX-capable. + */ + if ( index == XEN_SYSCTL_cpu_featureset_hvm_max && + test_bit(X86_FEATURE_MPX, host_fs) ) + set_bit(X86_FEATURE_MPX, fs); + + switch ( vendor ) + { + case VENDOR_AMD: + /* + * In order to mitigate Spectre, AMD dropped the LWP feature in + * microcode, to make space for MSR_PRED_CMD. No one used LWP, but it + * was visible to guests at the time. + */ + if ( index == XEN_SYSCTL_cpu_featureset_hvm_max ) + set_bit(X86_FEATURE_LWP, fs); + break; + + case VENDOR_INTEL: + /* + * MSR_ARCH_CAPS is just feature data, and we can offer it to guests + * unconditionally, although limit it to Intel systems as it is highly + * uarch-specific. + * + * In particular, the RSBA and RRSBA bits mean "you might migrate to a + * system where RSB underflow uses alternative predictors (a.k.a + * Retpoline not safe)", so these need to be visible to a guest in all + * cases, even when it's only some other server in the pool which + * suffers the identified behaviour. + * + * We can always run any VM which has previously (or will + * subsequently) run on hardware where Retpoline is not safe. + * Note: + * - The dependency logic may hide RRSBA for other reasons. + * - The max policy does not constitute a sensible configuration to + * run a guest in. + */ + set_bit(X86_FEATURE_ARCH_CAPS, fs); + set_bit(X86_FEATURE_RSBA, fs); + set_bit(X86_FEATURE_RRSBA, fs); + break; + } + } + + return 0; +} + uint32_t xc_get_cpu_featureset_size(void) { return FEATURESET_NR_ENTRIES; @@ -228,12 +371,7 @@ int xc_get_domain_cpu_policy(xc_interfac struct cpuid_domain_info { - enum - { - VENDOR_UNKNOWN, - VENDOR_INTEL, - VENDOR_AMD, - } vendor; + enum vendor vendor; bool hvm; uint64_t xfeature_mask; @@ -314,16 +452,7 @@ static int get_cpuid_domain_info(xc_inte int rc; cpuid(in, regs); - if ( regs[1] == 0x756e6547U && /* "GenuineIntel" */ - regs[2] == 0x6c65746eU && - regs[3] == 0x49656e69U ) - info->vendor = VENDOR_INTEL; - else if ( regs[1] == 0x68747541U && /* "AuthenticAMD" */ - regs[2] == 0x444d4163U && - regs[3] == 0x69746e65U ) - info->vendor = VENDOR_AMD; - else - info->vendor = VENDOR_UNKNOWN; + info->vendor = lookup_vendor(regs[1], regs[2], regs[3]); if ( xc_domain_getinfo(xch, domid, 1, &di) != 1 || di.domid != domid )
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