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charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/21/24 07:45, Sean Christopherson wrote: > On Wed, Nov 20, 2024, Dave Hansen wrote: >> The CPUID level dependency table will entirely zap X86_FEATURE_XSAVE > > What table is that? XSAVE depends on FXSR, but I can't find anything that clears > X86_FEATURE_XSAVE if cpuid_level < XSTATE_CPUID. Even if it did, dropping a > sanity check in a one-time path adds risk for almost no reward. arch/x86/kernel/cpu/common.c::cpuid_dependent_features[] It's hard to find because it hard-codes the leaf number: { X86_FEATURE_XSAVE, 0x0000000d }, Fixing that was my initial motivation for this series. As for removing the checks, I'd much rather have a super generic check in the CPUID helpers that have all the callers code something. Something like the attached patch? --------------31DaaGTZcHgscu02RE6el0q7 Content-Type: text/x-patch; charset=UTF-8; name="cpuid_count-warn.patch" Content-Disposition: attachment; filename="cpuid_count-warn.patch" Content-Transfer-Encoding: base64 CgotLS0KCiBiL2FyY2gveDg2L2luY2x1ZGUvYXNtL2NwdWlkLmggfCAgICA2ICsrKysrKwog Yi9hcmNoL3g4Ni9rZXJuZWwvY3B1L2NvbW1vbi5jIHwgICAzOCArKysrKysrKysrKysrKysr KysrKysrKysrKysrKysrKysrKysrKwogMiBmaWxlcyBjaGFuZ2VkLCA0NCBpbnNlcnRpb25z KCspCgpkaWZmIC1wdU4gYXJjaC94ODYvaW5jbHVkZS9hc20vY3B1aWQuaH5jcHVpZF9jb3Vu dC13YXJuIGFyY2gveDg2L2luY2x1ZGUvYXNtL2NwdWlkLmgKLS0tIGEvYXJjaC94ODYvaW5j bHVkZS9hc20vY3B1aWQuaH5jcHVpZF9jb3VudC13YXJuCTIwMjQtMTEtMjIgMDg6NTA6MTIu NjE4MTg2NjEwIC0wODAwCisrKyBiL2FyY2gveDg2L2luY2x1ZGUvYXNtL2NwdWlkLmgJMjAy NC0xMS0yMiAwOToxMDoxMi4xMTIyMTc5NDIgLTA4MDAKQEAgLTY0LDYgKzY0LDggQEAgbmF0 aXZlX2NwdWlkX3JlZyhlZHgpCiAjZGVmaW5lIF9fY3B1aWQJCQluYXRpdmVfY3B1aWQKICNl bmRpZgogCitleHRlcm4gdm9pZCBjaGVja19jcHVpZF9sZXZlbCh1bnNpZ25lZCBpbnQgbGV2 ZWwpOworCiAvKgogICogR2VuZXJpYyBDUFVJRCBmdW5jdGlvbgogICogY2xlYXIgJWVjeCBz aW5jZSBzb21lIGNwdXMgKEN5cml4IE1JSSkgZG8gbm90IHNldCBvciBjbGVhciAlZWN4CkBA IC03Myw2ICs3NSw4IEBAIHN0YXRpYyBpbmxpbmUgdm9pZCBjcHVpZCh1bnNpZ25lZCBpbnQg b3AKIAkJCSB1bnNpZ25lZCBpbnQgKmVheCwgdW5zaWduZWQgaW50ICplYngsCiAJCQkgdW5z aWduZWQgaW50ICplY3gsIHVuc2lnbmVkIGludCAqZWR4KQogeworCWNoZWNrX2NwdWlkX2xl dmVsKG9wKTsKKwogCSplYXggPSBvcDsKIAkqZWN4ID0gMDsKIAlfX2NwdWlkKGVheCwgZWJ4 LCBlY3gsIGVkeCk7CkBAIC04Myw2ICs4Nyw4IEBAIHN0YXRpYyBpbmxpbmUgdm9pZCBjcHVp ZF9jb3VudCh1bnNpZ25lZAogCQkJICAgICAgIHVuc2lnbmVkIGludCAqZWF4LCB1bnNpZ25l ZCBpbnQgKmVieCwKIAkJCSAgICAgICB1bnNpZ25lZCBpbnQgKmVjeCwgdW5zaWduZWQgaW50 ICplZHgpCiB7CisJY2hlY2tfY3B1aWRfbGV2ZWwob3ApOworCiAJKmVheCA9IG9wOwogCSpl Y3ggPSBjb3VudDsKIAlfX2NwdWlkKGVheCwgZWJ4LCBlY3gsIGVkeCk7CmRpZmYgLXB1TiBh cmNoL3g4Ni9rZXJuZWwvY3B1L2NvbW1vbi5jfmNwdWlkX2NvdW50LXdhcm4gYXJjaC94ODYv a2VybmVsL2NwdS9jb21tb24uYwotLS0gYS9hcmNoL3g4Ni9rZXJuZWwvY3B1L2NvbW1vbi5j fmNwdWlkX2NvdW50LXdhcm4JMjAyNC0xMS0yMiAwOTowNzo0My45MjI1OTE3MjAgLTA4MDAK KysrIGIvYXJjaC94ODYva2VybmVsL2NwdS9jb21tb24uYwkyMDI0LTExLTIyIDA5OjQyOjQ4 Ljk1MDk1MjUzOCAtMDgwMApAQCAtMjQyNSwzICsyNDI1LDQxIEBAIHZvaWQgX19pbml0IGFy Y2hfY3B1X2ZpbmFsaXplX2luaXQodm9pZCkKIAkgKi8KIAltZW1fZW5jcnlwdF9pbml0KCk7 CiB9CisKK3ZvaWQgY2hlY2tfY3B1aWRfbGV2ZWwodW5zaWduZWQgaW50IGxlYWYpCit7CisJ dW5zaWduZWQgaW50IHJlZ2lvbiA9IGxlYWYgPj4gNDsKKwlpbnQgbWF4X2xlYWY7CisKKwkv KgorCSAqIFRoZSBtYXggbGVhZiBpbiBhIHJlZ2lvbiBpcyBkaXNjb3ZlcmVkIGZyb20gdGhl IGZpcnN0CisJICogbGVhZi4gQWxsb3cgdGhpcyBraW5kIG9mIGRpc2NvdmVyeSB3aXRob3V0 IGNoZWNrczoKKwkgKi8KKwlpZiAoIShsZWFmICYgR0VOTUFTSygzLCAwKSkpCisJCXJldHVy bjsKKworCXN3aXRjaCAocmVnaW9uKSB7CisJCWNhc2UgMHgwMDAwOgorCQkJbWF4X2xlYWYg PSBib290X2NwdV9kYXRhLmNwdWlkX2xldmVsOworCQkJYnJlYWs7CisJCWNhc2UgMHg4MDAw OgorCQkJbWF4X2xlYWYgPSBib290X2NwdV9kYXRhLmV4dGVuZGVkX2NwdWlkX2xldmVsOwor CQkJYnJlYWs7CisJCWRlZmF1bHQ6CisJCQkvKiBPbmx5IGNoZWNrIHRoZSBiYXNpYyBhbmQg ZXh0ZW5kZWQgcmVnaW9uczogKi8KKwkJCXJldHVybjsKKwl9CisKKwkvKgorCSAqIFNraXAg Y2hlY2tzIGJlZm9yZSAtPmNwdWlkX2xldmVsIGlzIHBvcHVsYXRlZAorCSAqIGFuZCBvbiBD UFVzIHdpdGhvdXQgQ1BVSUQgc3VwcG9ydDoKKwkgKi8KKwlpZiAoIW1heF9sZWFmKQorCQly ZXR1cm47CisKKwlpZiAobGVhZiA8PSBtYXhfbGVhZikKKwkJcmV0dXJuOworCisJV0FSTl9P TkNFKDEsICJDUFVJRCByZWFkIGxlYWYgMHgleCBhYm92ZSBtYXggc3VwcG9ydGVkIGxlYWY6 IDB4JXgiLAorCQlsZWFmLCBtYXhfbGVhZik7Cit9Cl8K --------------31DaaGTZcHgscu02RE6el0q7--