From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 716D03FB074; Thu, 7 May 2026 14:01:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778162505; cv=none; b=eMaGSTuK6MlK5OqpUM+huARiuSqI4DUWF2wnVHilVMoJAkUGYIVU9ydrOk02luL98vqzbbyZL7PMGXNviQ01sb+CLlJppes/OfF7/bww2ETy6PviUZXGQL581GqimzyefnhiBz/LtsGRRwqcZX2HXtz8jIHSe1uulkP4kdGVuXo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778162505; c=relaxed/simple; bh=IF5F5PyLPu0tkKyhEJgsTExERa7huyFYBTZECT2UT6w=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=q6aRuFvV9EDu3kfoj4vvzf1+t1sWoYaXvgtH4MEHMAsdDmXcLV/uOOurLT2m68sQgFGGj4Qq5cYdr518gqe/MELSKWVhGVDpQoTbanJHnVmNWNlV4hDrR7ML7QZVI8d/0BETjwcfJuB7NwJSqcQktekP+Ra0Of1L+z4I2Jm6eXQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=desiato.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=DbXKWxcx; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=desiato.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="DbXKWxcx" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=MIME-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=v2uYTFauoEdbNV0MCEeBE4pilq8BPvcPfU8VFYBL7g0=; b=DbXKWxcxRz+2cTZSW+SZFCYACF pisNfMb5Uql34bQthraZHda1PmjKaIL0sLDe/cZ41qTL0WPxEN7WmZYcMMz+FHRpRYqyj/G4dDf3u +0aXySeLFnH0EOl8L3ypOAvFh0nKKt5bU6bznPMy9SoAOhVbDGGIAhUkGiCH7wskopY22+0193Ohh L9RhJQoErS9/XH32mHXyHbCG1fgwyKj0j5vjJZxUuMvQowGeFIxpqL9Gq5RxfLMpJH2au6K9EHH6n cJm/XomdqEpWley0ziOT/xwplA+zEzmPv8UMNpyhWzy0xBnQ4tH+OQEnjhGKOsEB8xnavdJfCNvuM g1hj6RIA==; Received: from [172.31.31.148] (helo=u09cd745991455d.ant.amazon.com) by desiato.infradead.org with esmtpsa (Exim 4.99.1 #2 (Red Hat Linux)) id 1wKzIH-00000003hzZ-32KW; Thu, 07 May 2026 14:01:38 +0000 Message-ID: <7a4f120bb41c77b5064b1e802bcc2928e0051b44.camel@infradead.org> Subject: Re: [PATCH v9 00/22] Enable FRED with KVM VMX From: David Woodhouse To: Maciej Wieczor-Retman Cc: Andrew Cooper , Xin Li , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, "Saenz Julienne, Nicolas" , pbonzini@redhat.com, seanjc@google.com, corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, luto@kernel.org, peterz@infradead.org, chao.gao@intel.com, hch@infradead.org, sohil.mehta@intel.com Date: Thu, 07 May 2026 15:01:37 +0100 In-Reply-To: References: <20251026201911.505204-1-xin@zytor.com> <7f93eb25874ddd13a1ad6e3c75785f11041c8b7f.camel@infradead.org> <1146015e19d441f135d81f376c158c938a7ba340.camel@infradead.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-mb2guqgUbQGk4omjz+gw" User-Agent: Evolution 3.52.3-0ubuntu1.1 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by desiato.infradead.org. See http://www.infradead.org/rpr.html --=-mb2guqgUbQGk4omjz+gw Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2026-05-07 at 15:53 +0200, Maciej Wieczor-Retman wrote: >=20 > My theory is that after 'int3' call the FRED event is handled elsewhere a= nd %rdi > is not preserved. So the original version of the assembly looks okay but = I was > thinking that int3 has side effects. >=20 > Below is the test output of the RIPs not matching when running the origin= al, > does that help in any way? Ah right, of course! +"fred_entrypoint_kernel:\n" + "movq %rsp, %rdi\n" + "call fred_handler\n" + ".byte 0xf2, 0x0f, 0x01, 0xca\n" /* ERETS */ + ".popsection\n" That needs to save the %rdi it's scribbling on, plus all the callee- clobbered registers that fred_handler() might use. --=-mb2guqgUbQGk4omjz+gw Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCD9Aw ggSOMIIDdqADAgECAhAOmiw0ECVD4cWj5DqVrT9PMA0GCSqGSIb3DQEBCwUAMGUxCzAJBgNVBAYT AlVTMRUwEwYDVQQKEwxEaWdpQ2VydCBJbmMxGTAXBgNVBAsTEHd3dy5kaWdpY2VydC5jb20xJDAi BgNVBAMTG0RpZ2lDZXJ0IEFzc3VyZWQgSUQgUm9vdCBDQTAeFw0yNDAxMzAwMDAwMDBaFw0zMTEx MDkyMzU5NTlaMEExCzAJBgNVBAYTAkFVMRAwDgYDVQQKEwdWZXJva2V5MSAwHgYDVQQDExdWZXJv a2V5IFNlY3VyZSBFbWFpbCBHMjCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAMjvgLKj jfhCFqxYyRiW8g3cNFAvltDbK5AzcOaR7yVzVGadr4YcCVxjKrEJOgi7WEOH8rUgCNB5cTD8N/Et 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