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X-CSE-ConnectionGUID: nwCrZwhaSju6Cte9OT+1cw== X-CSE-MsgGUID: 50mhvzedShmkckdtDvsbEg== X-IronPort-AV: E=McAfee;i="6800,10657,11632"; a="66788159" X-IronPort-AV: E=Sophos;i="6.20,249,1758610800"; d="scan'208";a="66788159" Received: from fmviesa006.fm.intel.com ([10.60.135.146]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Dec 2025 10:59:18 -0800 X-CSE-ConnectionGUID: 5BX6+0HtRfGSSuwchY/cwg== X-CSE-MsgGUID: 2Gy5TwZcTl6qxGnlwS2ypw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.20,249,1758610800"; d="scan'208";a="194952291" Received: from jdoman-mobl3.amr.corp.intel.com (HELO [10.125.108.81]) ([10.125.108.81]) by fmviesa006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Dec 2025 10:59:16 -0800 Content-Type: multipart/mixed; boundary="------------vc7s0RPLK54dAdS70enIaN0e" Message-ID: Date: Thu, 4 Dec 2025 10:59:15 -0800 Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [Patch v5 06/19] perf/x86: Add support for XMM registers in non-PEBS and REGS_USER To: Peter Zijlstra , Dapeng Mi Cc: Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Thomas Gleixner , Dave Hansen , Ian Rogers , Adrian Hunter , Jiri Olsa , Alexander Shishkin , Andi Kleen , Eranian Stephane , Mark Rutland , broonie@kernel.org, Ravi Bangoria , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Zide Chen , Falcon Thomas , Dapeng Mi , Xudong Hao , Kan Liang References: <20251203065500.2597594-1-dapeng1.mi@linux.intel.com> <20251203065500.2597594-7-dapeng1.mi@linux.intel.com> <20251204151735.GO2528459@noisy.programming.kicks-ass.net> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 12/4/25 07:17, Peter Zijlstra wrote: >> - Additionally, checking the TIF_NEED_FPU_LOAD flag alone is insufficient. >> Some corner cases, such as an NMI occurring just after the flag switches >> but still in kernel mode, cannot be handled. > Urgh.. Dave, Thomas, is there any reason we could not set > TIF_NEED_FPU_LOAD *after* doing the XSAVE (clearing is already done > after restore). > > That way, when an NMI sees TIF_NEED_FPU_LOAD it knows the task copy is > consistent. Something like the attached patch? I think that would be just fine. save_fpregs_to_fpstate() doesn't actually change the need for TIF_NEED_FPU_LOAD, so I don't think the ordering matters. --------------vc7s0RPLK54dAdS70enIaN0e Content-Type: text/x-patch; charset=UTF-8; name="tif-after-xsave.patch" Content-Disposition: attachment; filename="tif-after-xsave.patch" Content-Transfer-Encoding: base64 ZGlmZiAtLWdpdCBhL2FyY2gveDg2L2luY2x1ZGUvYXNtL2ZwdS9zY2hlZC5oIGIvYXJjaC94 ODYvaW5jbHVkZS9hc20vZnB1L3NjaGVkLmgKaW5kZXggODkwMDRmNGNhMjA4Li4yZDU3YTdi ZjU0MDYgMTAwNjQ0Ci0tLSBhL2FyY2gveDg2L2luY2x1ZGUvYXNtL2ZwdS9zY2hlZC5oCisr KyBiL2FyY2gveDg2L2luY2x1ZGUvYXNtL2ZwdS9zY2hlZC5oCkBAIC0zNiw4ICszNiw4IEBA IHN0YXRpYyBpbmxpbmUgdm9pZCBzd2l0Y2hfZnB1KHN0cnVjdCB0YXNrX3N0cnVjdCAqb2xk LCBpbnQgY3B1KQogCSAgICAhKG9sZC0+ZmxhZ3MgJiAoUEZfS1RIUkVBRCB8IFBGX1VTRVJf V09SS0VSKSkpIHsKIAkJc3RydWN0IGZwdSAqb2xkX2ZwdSA9IHg4Nl90YXNrX2ZwdShvbGQp OwogCi0JCXNldF90c2tfdGhyZWFkX2ZsYWcob2xkLCBUSUZfTkVFRF9GUFVfTE9BRCk7CiAJ CXNhdmVfZnByZWdzX3RvX2Zwc3RhdGUob2xkX2ZwdSk7CisJCXNldF90c2tfdGhyZWFkX2Zs YWcob2xkLCBUSUZfTkVFRF9GUFVfTE9BRCk7CiAJCS8qCiAJCSAqIFRoZSBzYXZlIG9wZXJh dGlvbiBwcmVzZXJ2ZWQgcmVnaXN0ZXIgc3RhdGUsIHNvIHRoZQogCQkgKiBmcHVfZnByZWdz X293bmVyX2N0eCBpcyBzdGlsbCBAb2xkX2ZwdS4gU3RvcmUgdGhlCg== --------------vc7s0RPLK54dAdS70enIaN0e--