[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH] x86/cpu-policy: Fix visibility of HTT/CMP_LEGACY in max policies
The block in recalculate_cpuid_policy() predates the proper split between default and max policies, and was a "slightly max for a toolstack which knows about it" capability. It didn't get transformed properly in Xen 4.14. Because Xen will accept a VM with HTT/CMP_LEGACY seen, they should be visible in the max polices. Keep the default policy matching host settings. This manifested as an incorrectly-rejected migration across XenServer's Xen 4.13 -> 4.17 upgrade, as Xapi is slowly growing the logic to check a VM against the target max policy. Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> --- CC: Jan Beulich <JBeulich@xxxxxxxx> CC: Roger Pau Monné <roger.pau@xxxxxxxxxx> CC: Wei Liu <wl@xxxxxxx> --- xen/arch/x86/cpu-policy.c | 29 ++++++++++++++++++++++------- 1 file changed, 22 insertions(+), 7 deletions(-) diff --git a/xen/arch/x86/cpu-policy.c b/xen/arch/x86/cpu-policy.c index c9b32bc17849..4f558e502e01 100644 --- a/xen/arch/x86/cpu-policy.c +++ b/xen/arch/x86/cpu-policy.c @@ -464,6 +464,16 @@ static void __init guest_common_max_feature_adjustments(uint32_t *fs) raw_cpu_policy.feat.clwb ) __set_bit(X86_FEATURE_CLWB, fs); } + + /* + * Topology information inside the guest is entirely at the toolstack's + * disgression, and bears no relationship to the host we're running on. + * + * HTT identifies p->basic.lppp as valid + * CMP_LEGACY identifies p->extd.nc as valid + */ + __set_bit(X86_FEATURE_HTT, fs); + __set_bit(X86_FEATURE_CMP_LEGACY, fs); } static void __init guest_common_default_feature_adjustments(uint32_t *fs) @@ -514,6 +524,18 @@ static void __init guest_common_default_feature_adjustments(uint32_t *fs) __clear_bit(X86_FEATURE_CLWB, fs); } + /* + * Topology information is at the toolstack's discretion so these are + * unconditionally set in max, but pick a default which matches the host. + */ + __clear_bit(X86_FEATURE_HTT, fs); + if ( cpu_has_htt ) + __set_bit(X86_FEATURE_HTT, fs); + + __clear_bit(X86_FEATURE_CMP_LEGACY, fs); + if ( cpu_has_cmp_legacy ) + __set_bit(X86_FEATURE_CMP_LEGACY, fs); + /* * On certain hardware, speculative or errata workarounds can result in * TSX being placed in "force-abort" mode, where it doesn't actually @@ -861,13 +883,6 @@ void recalculate_cpuid_policy(struct domain *d) } } - /* - * Allow the toolstack to set HTT and CMP_LEGACY. These bits - * affect how to interpret topology information in other cpuid leaves. - */ - __set_bit(X86_FEATURE_HTT, max_fs); - __set_bit(X86_FEATURE_CMP_LEGACY, max_fs); - /* * 32bit PV domains can't use any Long Mode features, and cannot use * SYSCALL on non-AMD hardware. -- 2.30.2
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