From nobody Tue Dec 23 18:09:18 2025 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 CB72638DDE; Wed, 31 Jan 2024 21:14:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706735685; cv=none; b=Kf8Y+oa2CAoUp7de/sWjkglDj6x6OwmfhJrd+dm9mBCI7nmUuNRTKuqWbqIeG8RRazlwW3LqOyTFnV9SMBj3qWjSJKNkKw3tCKcmgLvJkVXTtxZmNEZ/J5RfNYAGjn6wX1KV0fzvnsknX7s3kJRFxpqZIUzKufA/k82SpEiBphc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706735685; c=relaxed/simple; bh=DUdu1UUn6wALW1cj2l8XknGX0U2NFDxrahheQj1928I=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=QY6M7oQZyH4+LeX5P4WgBIvgyBNFZpvQS1eKnz/rN3tvVMwvsZp2bHh7sIqcjXtL3682YvLMNIMItzMDK1kS8UlgQTybYvDPOQw3yiSDY7B7Xri/RsfrFzkQse5u1+abFIjZVAT06rYaJ25cf5oTGi9oNp7JCFZ2ByAG6XxiKC8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=xIZIf12b; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=N0BwHDMF; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="xIZIf12b"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="N0BwHDMF" Date: Wed, 31 Jan 2024 21:14:41 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1706735682; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=K90tbVXhZFmfJhns82LQ9QMx3cTg6w8J9UyWPRkjn9s=; b=xIZIf12bbP363ruX57tRSlkAo6DK4z8NB/sO/fqduaFeJ2w7tZ0xdLsR+9sqOusJcMmt7d 4WfcpUWcO0qveTdPQ+X7tvM/hfhn/Tqnk+W8HcS2QnkMDj1Jlc9tsiA4D8IBA9kUFW5hnc x0bgPZXt/w/bgKY7sA3tnPLPODHUsX4RPBGNBG4GemiC4ZieUwmaNK14IUEqOjij0hfU+h hAT9h/dncRXfIs9j5oh5EZbgVaIslVH+bONrXDUN5r8LbGRPT89TN7vlva39L8gIBRx89i zFUNalt6xvx0mJcBE8Nd3KAcOrAa/G1AS3LR9AxpD7sv/+UoXYYisQqmiIz0wQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1706735682; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=K90tbVXhZFmfJhns82LQ9QMx3cTg6w8J9UyWPRkjn9s=; b=N0BwHDMF0J5NZOZRYZkYlcPFpbOtG7Vwso5QPJeSv7fP8f11110XMXnEich+7qp1ZON2Fr wVz9QFzb5EmKxoBg== From: "tip-bot2 for Xin Li" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/fred] x86/entry: Add fred_entry_from_kvm() for VMX to handle IRQ/NMI Cc: Sean Christopherson , Thomas Gleixner , Xin Li , "Borislav Petkov (AMD)" , Shan Kang , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20231205105030.8698-32-xin3.li@intel.com> References: <20231205105030.8698-32-xin3.li@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <170673568142.398.18052347481450991187.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the x86/fred branch of tip: Commit-ID: 2e670358ec1829238c99fbff178e285d3eb43ef1 Gitweb: https://git.kernel.org/tip/2e670358ec1829238c99fbff178e285d3= eb43ef1 Author: Xin Li AuthorDate: Tue, 05 Dec 2023 02:50:20 -08:00 Committer: Borislav Petkov (AMD) CommitterDate: Wed, 31 Jan 2024 22:03:16 +01:00 x86/entry: Add fred_entry_from_kvm() for VMX to handle IRQ/NMI In IRQ/NMI induced VM exits, KVM VMX needs to execute the respective handlers, which requires the software to create a FRED stack frame, and use it to invoke the handlers. Add fred_irq_entry_from_kvm() for this job. Export fred_entry_from_kvm() because VMX can be compiled as a module. Suggested-by: Sean Christopherson Suggested-by: Thomas Gleixner Signed-off-by: Xin Li Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov (AMD) Tested-by: Shan Kang Link: https://lore.kernel.org/r/20231205105030.8698-32-xin3.li@intel.com --- arch/x86/entry/entry_64_fred.S | 77 +++++++++++++++++++++++++++++++++- arch/x86/entry/entry_fred.c | 14 ++++++- arch/x86/include/asm/fred.h | 18 ++++++++- 3 files changed, 109 insertions(+) diff --git a/arch/x86/entry/entry_64_fred.S b/arch/x86/entry/entry_64_fred.S index 7fe2722..a02bc6f 100644 --- a/arch/x86/entry/entry_64_fred.S +++ b/arch/x86/entry/entry_64_fred.S @@ -3,8 +3,11 @@ * The actual FRED entry points. */ =20 +#include + #include #include +#include =20 #include "calling.h" =20 @@ -52,3 +55,77 @@ SYM_CODE_START_NOALIGN(asm_fred_entrypoint_kernel) FRED_EXIT ERETS SYM_CODE_END(asm_fred_entrypoint_kernel) + +#if IS_ENABLED(CONFIG_KVM_INTEL) +SYM_FUNC_START(asm_fred_entry_from_kvm) + push %rbp + mov %rsp, %rbp + + UNWIND_HINT_SAVE + + /* + * Both IRQ and NMI from VMX can be handled on current task stack + * because there is no need to protect from reentrancy and the call + * stack leading to this helper is effectively constant and shallow + * (relatively speaking). Do the same when FRED is active, i.e., no + * need to check current stack level for a stack switch. + * + * Emulate the FRED-defined redzone and stack alignment. + */ + sub $(FRED_CONFIG_REDZONE_AMOUNT << 6), %rsp + and $FRED_STACK_FRAME_RSP_MASK, %rsp + + /* + * Start to push a FRED stack frame, which is always 64 bytes: + * + * +--------+-----------------+ + * | Bytes | Usage | + * +--------+-----------------+ + * | 63:56 | Reserved | + * | 55:48 | Event Data | + * | 47:40 | SS + Event Info | + * | 39:32 | RSP | + * | 31:24 | RFLAGS | + * | 23:16 | CS + Aux Info | + * | 15:8 | RIP | + * | 7:0 | Error Code | + * +--------+-----------------+ + */ + push $0 /* Reserved, must be 0 */ + push $0 /* Event data, 0 for IRQ/NMI */ + push %rdi /* fred_ss handed in by the caller */ + push %rbp + pushf + mov $__KERNEL_CS, %rax + push %rax + + /* + * Unlike the IDT event delivery, FRED _always_ pushes an error code + * after pushing the return RIP, thus the CALL instruction CANNOT be + * used here to push the return RIP, otherwise there is no chance to + * push an error code before invoking the IRQ/NMI handler. + * + * Use LEA to get the return RIP and push it, then push an error code. + */ + lea 1f(%rip), %rax + push %rax /* Return RIP */ + push $0 /* Error code, 0 for IRQ/NMI */ + + PUSH_AND_CLEAR_REGS clear_bp=3D0 unwind_hint=3D0 + movq %rsp, %rdi /* %rdi -> pt_regs */ + call __fred_entry_from_kvm /* Call the C entry point */ + POP_REGS + ERETS +1: + /* + * Objtool doesn't understand what ERETS does, this hint tells it that + * yes, we'll reach here and with what stack state. A save/restore pair + * isn't strictly needed, but it's the simplest form. + */ + UNWIND_HINT_RESTORE + pop %rbp + RET + +SYM_FUNC_END(asm_fred_entry_from_kvm) +EXPORT_SYMBOL_GPL(asm_fred_entry_from_kvm); +#endif diff --git a/arch/x86/entry/entry_fred.c b/arch/x86/entry/entry_fred.c index 3be0269..6ecc08b 100644 --- a/arch/x86/entry/entry_fred.c +++ b/arch/x86/entry/entry_fred.c @@ -257,3 +257,17 @@ __visible noinstr void fred_entry_from_kernel(struct p= t_regs *regs) =20 return fred_bad_type(regs, error_code); } + +#if IS_ENABLED(CONFIG_KVM_INTEL) +__visible noinstr void __fred_entry_from_kvm(struct pt_regs *regs) +{ + switch (regs->fred_ss.type) { + case EVENT_TYPE_EXTINT: + return fred_extint(regs); + case EVENT_TYPE_NMI: + return fred_exc_nmi(regs); + default: + WARN_ON_ONCE(1); + } +} +#endif diff --git a/arch/x86/include/asm/fred.h b/arch/x86/include/asm/fred.h index 16a64ff..2fa9f34 100644 --- a/arch/x86/include/asm/fred.h +++ b/arch/x86/include/asm/fred.h @@ -9,6 +9,7 @@ #include =20 #include +#include =20 /* * FRED event return instruction opcodes for ERET{S,U}; supported in @@ -62,12 +63,29 @@ static __always_inline unsigned long fred_event_data(st= ruct pt_regs *regs) =20 void asm_fred_entrypoint_user(void); void asm_fred_entrypoint_kernel(void); +void asm_fred_entry_from_kvm(struct fred_ss); =20 __visible void fred_entry_from_user(struct pt_regs *regs); __visible void fred_entry_from_kernel(struct pt_regs *regs); +__visible void __fred_entry_from_kvm(struct pt_regs *regs); + +/* Can be called from noinstr code, thus __always_inline */ +static __always_inline void fred_entry_from_kvm(unsigned int type, unsigne= d int vector) +{ + struct fred_ss ss =3D { + .ss =3D__KERNEL_DS, + .type =3D type, + .vector =3D vector, + .nmi =3D type =3D=3D EVENT_TYPE_NMI, + .lm =3D 1, + }; + + asm_fred_entry_from_kvm(ss); +} =20 #else /* CONFIG_X86_FRED */ static __always_inline unsigned long fred_event_data(struct pt_regs *regs)= { return 0; } +static __always_inline void fred_entry_from_kvm(unsigned int type, unsigne= d int vector) { } #endif /* CONFIG_X86_FRED */ #endif /* !__ASSEMBLY__ */