From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f198.google.com (mail-pg1-f198.google.com [209.85.215.198]) (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 B91711DED5C for ; Thu, 27 Aug 2026 17:33:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.198 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787852029; cv=none; b=XHmMnTFS5sFLtqik7u2Bdprnu1NDAIrT7J+PwOmsh6ndbB3qTI+lMKcxADD4l3iwzO+o03imk81bnxH/qW90HhkmPRJM/f6tYU0qqhCI5aQGTUDtZtglMbpx9l4Ba+ZnZb3+6Usy/4ybsdjCbzu1Oz/0gqzZGGvQrScHT0Wd4tc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787852029; c=relaxed/simple; bh=mQBC4ZInVAewkqG/uEXWTGggvkR3ICtM2BRnNn8cVvU=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=Ib/4C6rV/oPcOaxF4VLRBkyP1D1UIQVbXsn3/+ztgfl8xOFZn0Aq3iG1eFCdiy6f6nS2JmI+eVQSJXMTUMd8TLzK9xK75VS1aRFXtjyxGngJux+4SNmQ0CYM67RAGlic8QJ6ZbJpJmdsv2T8gcTustlZi4vmvIN75TfOYsQ+L/M= 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=n/TMbnQo; arc=none smtp.client-ip=209.85.215.198 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="n/TMbnQo" Received: by mail-pg1-f198.google.com with SMTP id 41be03b00d2f7-cc1c1cc5206so132620a12.3 for ; Thu, 27 Aug 2026 10:33:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1787852028; x=1788456828; darn=vger.kernel.org; h=content-transfer-encoding:content-type:cc:to:from:subject :message-id:references:mime-version:in-reply-to:date:from:to:cc :subject:date:message-id:reply-to:content-type; bh=A0Qync/lpbri7HzFIMP3cl9pdBpZkpuA/yuJrcyMO2s=; b=n/TMbnQoerCb/xA6HZywi0Wbc8OnPQ4N9bSILkh81hQXNmo6cNEflo97gBqFs8K8/7 ekmoAbV9L1dAvZqtLdRyP7E1LQ+lcJRE/iwIV2k5fbb9gKMb225rQnD9ldB+J+1ri7A8 yiZS1OX2+21IqkTNqFJOZsvzt67NEbLEu7bXA9gbVbiab2WkJbf3f/j1b3z+wlHElJb5 piHftlkDyC5DnVbRV3SI/WSGjUsin6KAa8iKOm+GnyLo0onDc0AjBWa7UurZlZt1fhhF VetCQXjikWSNQ87YXGeoMwWT5kBnjcFWBuujJ49TWIb38m7QnEV1YX0pYtmNxJlEXPFO PTVg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1787852028; x=1788456828; h=content-transfer-encoding:content-type: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 :content-type; bh=A0Qync/lpbri7HzFIMP3cl9pdBpZkpuA/yuJrcyMO2s=; b=kOWbrFzl0EA9IkTwTB3N2n5o4CHZ0YSnplPYKAMl/EFDBxLtzNLYxN3vatBtM5OiXH 0vB8GQQK4oFPCWRCIL3KqjjIK5tg6rSIqKweZusulTWn2Zy/9cWHjMXC4OLOQZQ0bUbd 7Z5zjrIn+D+3lTwrjk4t269msbjG03yWzim8RBZpu1ymuyCv4Pq5i4kt5E7nDjWq6Npu rSDfbnajrrY8cX+DdB8ee2oewAO7qz8s7gYvU5N9WeQ5i3zzLLyn415z/u7RDm1UsqoQ BhYgcO6ZlAPYHRH03x3N1HBDorUzSwmBGvcScregVTgfUoS5ImzPG+rHphXsle8T+ZYr ueYA== X-Forwarded-Encrypted: i=1; AHgh+RpD5sQxlGfeVxxsWeHTGKXu8bOKe8n7OLU1glvXeXTfJbAkxp0ffncYaN/pKBHnebVYi6z3Fwt9qggNNI8=@vger.kernel.org X-Gm-Message-State: AFuF++lZYVczgvA9JuYmrljz5mVKFGU+sRJ8eUhUh6Hi7I9a2UzC1mry 3GcMa2xPsEs47hFMyWfkBEupBWa85ugnygZG8sAnVXkQ6RyqJuoSRINJ4FwS9QF6SoSeisbt8OK 337/x/A== X-Received: from pgah16.prod.google.com ([2002:a05:6a02:4e90:b0:cc1:d46e:147a]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:b7a7:b0:3be:b0b3:3962 with SMTP id adf61e73a8af0-3d268ef9e07mr994999637.9.1787852027735; Thu, 27 Aug 2026 10:33:47 -0700 (PDT) Date: Thu, 27 Aug 2026 10:33:47 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260826233919.998904-1-seanjc@google.com> <20260826233919.998904-13-seanjc@google.com> Message-ID: Subject: Re: [PATCH v3 12/13] KVM: selftests: Dedup assembly code for VMLAUNCH and VMRESUME From: Sean Christopherson To: Yosry Ahmed Cc: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, f734222792@gmail.com, Vitaly Kuznetsov , Sashiko Bot Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Thu, Aug 27, 2026, Yosry Ahmed wrote: > On Thu, Aug 27, 2026 at 10:17=E2=80=AFAM Sean Christopherson wrote: > > eVMCS is a memory operand, i.e. it's MOV RSP, [evmcs->host_rip]. The e= xisting > > evmcs_{vmresume,vmlaunch}() code is rather stupid and loads the address= into a > > register, and then manually encodes MOV RSP, []. >=20 > Can't we keep it as a register operand just to avoid vmwrite_operand? > Does it actually hurt in any way? ... > > diff --git tools/testing/selftests/kvm/lib/x86/vmx.c tools/testing/self= tests/kvm/lib/x86/vmx.c > > index 1a8515de42b0..b5efd10950c7 100644 > > --- tools/testing/selftests/kvm/lib/x86/vmx.c > > +++ tools/testing/selftests/kvm/lib/x86/vmx.c > > @@ -179,7 +179,10 @@ void load_vmcs(struct vmx_pages *vmx) > > vmclear(vmx->shadow_vmcs_gpa); > > } > > > > -#define __BUILD_VMX_VM_ENTRY_HELPER(insn, prefix, vmwrite_insn, vmwrit= e_operand, \ > > +const u64 HOST_RSP_ENCODING =3D HOST_RSP; > > +const u64 HOST_RIP_ENCODING =3D HOST_RIP; > > + > > +#define __BUILD_VMX_VM_ENTRY_HELPER(insn, prefix, vmwrite_insn, = \ > > __host_rsp, __host_rip) = \ > > static int __##prefix##_##insn(void) = \ > > { = \ > > @@ -196,16 +199,17 @@ static int __##prefix##_##insn(void) = \ > > VMX_SWITCH_GPRS_ASM = \ > > "pop %%rax;" = \ > > : [ret]"=3D&a"(ret) = \ > > - : [host_rsp]__stringify(vmwrite_operand)(_= _host_rsp), \ > > - [host_rip]__stringify(vmwrite_operand)(_= _host_rip), \ > > + : [host_rsp]"m"(__host_rsp), = \ > > + [host_rip]"m"(__host_rip), = \ >=20 > I suppose we can use "r" here though? No, because then the encoding for VMWRITE needs to be: vmwrite %%rsp, %[host_rsp] but for MOV/eVMCS needs to be: mov %%rsp, (%[host_rsp]) Have fun feeding the '(' and ')' into the asm blob :-)