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 532CB2F8E82; Thu, 7 May 2026 23:00:28 +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=1778194831; cv=none; b=bkEwIGGGwIMOytNnERnGtUHnmv8Gx7iM9xEtxCrFX7Kj6yeSo/S0QOSW1oUT67Bi1BSwv1e7TtmdJ2KAYzb89VuxpGTmk1QuKlOc7e6RNsRHjYkCpaknN+V/qgagtkloVjsYSBp33PtRMkfI9vY8cQQeT6Bw/S+IeASgcIXs0Cc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778194831; c=relaxed/simple; bh=6Dm4hXH4o6oGBRf9PHFm5jvQg9V0nkMjf8aRjNzhHY0=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=H9BRf1TOC735ZDIIBAgtgnGR5a9AYEYXOzxVjzjj4HJOvZUVD6dcahnevcwM7s7y47gjk1YfdZOc5FckE7QTqWuaB0N5L4WobRkWjfkyiytFVZ/o/UebOru6uHfpa5ZLMKNHNm9fqURAVhtDnnZX1OWapgB/A7hCCfPxCRbTmrs= 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=hylZe76Q; 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="hylZe76Q" 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=1eyRFt7KxgxNwPrjXchyQHWQHHMjRq6rE0uvPcHhvSg=; b=hylZe76QEMyDYdB4YSvznQmLGO uBolLIN+lCsQn5ayD32gwRVvC+1NGM49Ih3Y/gW6T4xk+MkVhRmQpeIcBFFnuu/cLde8xnJ5YUIWA kpjv/2e7dB/W5PlzqtSkI5l9U2xfqSz0qGgArktAZQgUmToIBJ5kBQWRk+klLDqQhyqD6kezpHX4h ydb6tq0iTId2JPVRNR28Nvy7fxDis052lyCOoZEVV4ttGPhtNDKjw5yqFUJryebb/gTZX3OfgDzah n6rHRNMOR4O4OP8986MwCPbp7X7V6ViQGWb5KdtCn3uy6aS2bvtF+IKXiW8AjOj4aPyE3nV/5O8lf O4bwvqrA==; 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 1wL7hd-00000004kSN-15os; Thu, 07 May 2026 23:00:21 +0000 Message-ID: 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: Fri, 08 May 2026 00:00:21 +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="=-D33cGU03nwedIdd4gfI2" 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 --=-D33cGU03nwedIdd4gfI2 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. Please could you try the version at https://git.infradead.org/?p=3Dusers/dwmw2/linux.git;a=3Dcommitdiff;h=3Dfre= d or this incremental patch: diff --git a/tools/testing/selftests/kvm/x86/int1_fred_test.c b/tools/testi= ng/selftests/kvm/x86/int1_fred_test.c index 7ffb54b56047..b91600abda62 100644 --- a/tools/testing/selftests/kvm/x86/int1_fred_test.c +++ b/tools/testing/selftests/kvm/x86/int1_fred_test.c @@ -74,7 +74,7 @@ static volatile uint64_t fred_ss_value; static volatile uint64_t fred_saved_rip; static volatile bool fred_handler_called; =20 -static void __used fred_handler(struct fred_stack_frame *frame) +static __attribute__((used)) void fred_handler(struct fred_stack_frame *fr= ame) { fred_ss_value =3D frame->ss; fred_saved_rip =3D frame->rip; @@ -99,8 +99,41 @@ asm( /* Pad to +256 for ring 0 entry */ ".org fred_entrypoint + 256, 0xcc\n" "fred_entrypoint_kernel:\n" - "movq %rsp, %rdi\n" + /* Save all GPRs =E2=80=94 exception must be transparent to interrupted c= ode */ + "pushq %rax\n" + "pushq %rcx\n" + "pushq %rdx\n" + "pushq %rbx\n" + "pushq %rbp\n" + "pushq %rsi\n" + "pushq %rdi\n" + "pushq %r8\n" + "pushq %r9\n" + "pushq %r10\n" + "pushq %r11\n" + "pushq %r12\n" + "pushq %r13\n" + "pushq %r14\n" + "pushq %r15\n" + /* Pass pointer to FRED stack frame (above our saved regs) */ + "leaq 120(%rsp), %rdi\n" "call fred_handler\n" + /* Restore all GPRs */ + "popq %r15\n" + "popq %r14\n" + "popq %r13\n" + "popq %r12\n" + "popq %r11\n" + "popq %r10\n" + "popq %r9\n" + "popq %r8\n" + "popq %rdi\n" + "popq %rsi\n" + "popq %rbp\n" + "popq %rbx\n" + "popq %rdx\n" + "popq %rcx\n" + "popq %rax\n" ".byte 0xf2, 0x0f, 0x01, 0xca\n" /* ERETS */ ".popsection\n" ); --=-D33cGU03nwedIdd4gfI2 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCD9Aw 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