From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f202.google.com (mail-pg1-f202.google.com [209.85.215.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 832663A5E91 for ; Tue, 16 Jun 2026 18:21:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781634065; cv=none; b=S4R+wU//8NNgRGwsL7IDL5xsbeuAswx5GwMaKDN0azZGdeJjpJsup0bMAVpmLi7xHubMXMYAMFGFRqArrhaL0YA3icG3Z2g6YKsW514b044tx/If5xCZBObbvOPwFz4tPdYWUon8ZffWbWJqmQ4JspP8kjfQOBSC9BSBSTIbESs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781634065; c=relaxed/simple; bh=0tSUUNVDEBGwYBjppBS1BH3TrzovrW9yOtoZpZdMF8Q=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=IDRhSoolOCq8XqK/xwYakrnXL7GKZ7UNbMM2gQXB55rljDDNH/lcMToITScwJeFaBG1MVNa22DVEDYvXnQHPU+I7nZ2y4lFig2E/zXWu4y5xvg06VUQb29K/rfXs/QjJeA2VnQgQ+9ceVcKZfDNZP7B51FLjbWrQMTZfRDLFvXA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=dbo1XmI2; arc=none smtp.client-ip=209.85.215.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="dbo1XmI2" Received: by mail-pg1-f202.google.com with SMTP id 41be03b00d2f7-c8628dc1802so5167327a12.2 for ; Tue, 16 Jun 2026 11:21:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1781634063; x=1782238863; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=PDGQwmie0FsFOW5zpiubju2q1B2vV8kB05baSk3HG50=; b=dbo1XmI2HdZ9FlZn05IJSPRX8vG6iJEUl6iYRtinBXhtr2pbjZzvNu8RUy6ff2y1cH 3rRTOxlru6/43NXpLPlntN32wW/23Yk87gbTVUcA+BEKgnb1YYHLD5ircXSpwNmTLUDy xciTKSawcGYQbIrdpiGMTcvYfaJ4kyYu6FDTvFumkZbQFENKatkCdo3bLIt62hH3r5sw k3nsQEt1osL1svOlVlNvDHqbfxJoLkNUaZSPw3y8YePhAFet7FnRg/la8n1QVPSodBnq J5zG6DXlg/3AtylA8e7QTYEidKhV59/3AnX+ostTY9v5l1eW28STKGod/6Je9hCM+/uX /gog== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1781634063; x=1782238863; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=PDGQwmie0FsFOW5zpiubju2q1B2vV8kB05baSk3HG50=; b=ZiOHfTdIJUoyA51+5l/ie+Ob07TJ1KH6W8DYDJR7ZC5ZGJfbsWCqy6NF5eT6Qy+O7/ c8agvuke/3GVexrTax+OPUGhjRjtO83nKHYoqtzDEtnU6zVPNCC4YFVc+JVeDcHTjv7q cSDVJCcL+1QFOH4ipk1VFMLC9vup2d9iPbkPsM1XrB4zgiICmwvpRhlAW/EX9EbXMXdT zFvKke9PbTGmAUi3mJ7GD+TdbNIr7G95eOASuv7wJj5S+zKG4q2rb3jByUeyYtvpwT8D 06arMk5trwZ6cQ5q1pRwAB4UTCkbFuXCyB8EFA3zRpOTnQKK3GGI2bAeRvFwnOMLGkMV q9yQ== X-Forwarded-Encrypted: i=1; AFNElJ/ldOUg/R4Mn1mpJ5It3PjjiOhJpwjYG32zwvvp/76rVYzxIoul7k7z0Ids/CoRE28LLBbqF0klMP26e4s=@vger.kernel.org X-Gm-Message-State: AOJu0YzP3bYIevHDL+YRvcBYw1SKf1WWlwBveyQcPrcrkPjbzhb9mX7M vw5MbujUEMYyDldRqGjHfWt++xvhdEpmsVFEtsM7pp9MNA1TTdZ61goByznIPqdfDB+qRaZcopX qGU/Dlw== X-Received: from pfh18.prod.google.com ([2002:a05:6a00:12d2:b0:843:492b:a9f6]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:a211:b0:83e:e897:a394 with SMTP id d2e1a72fcca58-8452442d041mr320027b3a.7.1781634062694; Tue, 16 Jun 2026 11:21:02 -0700 (PDT) Date: Tue, 16 Jun 2026 11:20:53 -0700 In-Reply-To: <20260521-tdx-selftests-v13-v13-20-6983ae4c3a4d@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260521-tdx-selftests-v13-v13-0-6983ae4c3a4d@google.com> <20260521-tdx-selftests-v13-v13-20-6983ae4c3a4d@google.com> Message-ID: Subject: Re: [PATCH v13 20/22] KVM: selftests: Implement MMIO WRITE for the TDX VM From: Sean Christopherson To: Lisa Wang Cc: Andrew Jones , Ackerley Tng , Binbin Wu , Chao Gao , Chenyi Qiang , Dave Hansen , Erdem Aktas , Ira Weiny , Isaku Yamahata , Kiryl Shutsemau , linux-kselftest@vger.kernel.org, Paolo Bonzini , "Pratik R. Sampat" , Reinette Chatre , Rick Edgecombe , Roger Wang , Ryan Afranji , Sagi Shahar , Shuah Khan , Oliver Upton , Jeremiah McReynolds , kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, x86@kernel.org Content-Type: text/plain; charset="us-ascii" On Thu, May 21, 2026, Lisa Wang wrote: > diff --git a/tools/testing/selftests/kvm/include/x86/tdx/tdx.h b/tools/testing/selftests/kvm/include/x86/tdx/tdx.h > new file mode 100644 > index 000000000000..810ca7423c84 > --- /dev/null > +++ b/tools/testing/selftests/kvm/include/x86/tdx/tdx.h > @@ -0,0 +1,16 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +#ifndef SELFTESTS_TDX_TDX_H > +#define SELFTESTS_TDX_TDX_H > + > +#include > + > +enum mmio_size { > + MMIO_SIZE_1B = 1, > + MMIO_SIZE_2B = 2, > + MMIO_SIZE_4B = 4, > + MMIO_SIZE_8B = 8 This is absurd. Either open code the literals or use sizeof() where appropriate. > +}; > + > +u64 tdx_mmio_write(u64 address, enum mmio_size size, u64 data_in); > + > +#endif // SELFTESTS_TDX_TDX_H > diff --git a/tools/testing/selftests/kvm/lib/x86/tdx/tdx.c b/tools/testing/selftests/kvm/lib/x86/tdx/tdx.c > new file mode 100644 > index 000000000000..f19be79fe11f > --- /dev/null > +++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdx.c > @@ -0,0 +1,30 @@ > +// SPDX-License-Identifier: GPL-2.0-only > + > +#include "tdx/tdx.h" > + > +#define TDG_VP_VMCALL 0 > +#define TDG_VP_VMCALL_VE_REQUEST_MMIO 48 > +#define TDVMCALL_MMIO_WRITE 1 > +#define TDVMCALL_EXPOSE_REGS_MASK 0xFC00 > + > +u64 tdx_mmio_write(u64 address, enum mmio_size size, u64 data_in) > +{ > + register u64 r10_reg asm("r10") = TDG_VP_VMCALL; > + register u64 r11_reg asm("r11") = TDG_VP_VMCALL_VE_REQUEST_MMIO; > + register u64 r12_reg asm("r12") = size; > + register u64 r13_reg asm("r13") = TDVMCALL_MMIO_WRITE; > + register u64 r14_reg asm("r14") = address; > + register u64 r15_reg asm("r15") = data_in; > + register u64 rax_reg asm("rax") = TDG_VP_VMCALL; > + register u64 rcx_reg asm("rcx") = TDVMCALL_EXPOSE_REGS_MASK; This needs to be proper assembly, i.e. in a .S file. Using register like this is *extremely* dangerous, because the compiler is (stupidly) allowed to clobber registers between their declarations/initialization and their consumption in the asm() blob. > + > + asm volatile( > + ".byte 0x66,0x0f,0x01,0xcc" /* tdcall */ > + : "+r" (r10_reg), "+r" (r11_reg) > + : "r" (r12_reg), "r" (r13_reg), "r" (r14_reg), "r" (r15_reg), > + "r" (rax_reg), "r" (rcx_reg) > + : "cc", "memory" > + ); > + > + return r10_reg; > +} > > -- > 2.54.0.746.g67dd491aae-goog >