From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mail-ej1-f42.google.com (mail-ej1-f42.google.com [209.85.218.42])
 by mx.groups.io with SMTP id smtpd.web10.35123.1674611104901529173
 for <devel@edk2.groups.io>;
 Tue, 24 Jan 2023 17:45:05 -0800
Authentication-Results: mx.groups.io;
 dkim=pass header.i=@google.com header.s=20210112 header.b=eQg3sWvV;
 spf=pass (domain: google.com, ip: 209.85.218.42, mailfrom: lisik@google.com)
Received: by mail-ej1-f42.google.com with SMTP id ss4so43698815ejb.11
        for <devel@edk2.groups.io>; Tue, 24 Jan 2023 17:45:04 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=google.com; s=20210112;
        h=cc:to:subject:message-id:date:from:in-reply-to:references
         :mime-version:from:to:cc:subject:date:message-id:reply-to;
        bh=bcQ/j1jNPc8XW+hXXv3TqqSs0egZ0ecbRIxB2KmwDgQ=;
        b=eQg3sWvV+pRHxLkMfQFCul9sN32RzobVyONacHrzXr/eC4WS1JbVW4nT1bQ6uPvO8m
         q/c/fTh7ZYc4JCmTFy0xL4kldkaoDcYJkEQObGr3o7EiHe2llBIhtQXeJzQbrEiO+Pbu
         EgbhbERyGMdrpkSsCFPHUNPNa3NtxEIA5SEmwT2V0ypa2IIlYdXfysG7H/Nqum/HF5LE
         vOuLfkYroe6Li1c3sgrD+yQwafzs+bAcnv1yBKp6A+rgfcmhn6wvaijEb1JeV5m+Xvjk
         ohtmVL3VgwMlAdyRbUKapSbxFBnUQrZjQLeajsy1G15D9Sx3siNSqR/2K+Kj6zZ1Mc8b
         nGzQ==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=1e100.net; s=20210112;
        h=cc:to:subject:message-id:date:from:in-reply-to:references
         :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id
         :reply-to;
        bh=bcQ/j1jNPc8XW+hXXv3TqqSs0egZ0ecbRIxB2KmwDgQ=;
        b=BlnqZYtVGuG4vmC5u7YGvnsqfC4eiJFKR03QmOz7vyy9Jk4MHKGqZD/r9wHeKkWZnA
         cZMQLYtVqZHk5j17pAS4JIj/rS8BR01iGI1VqU4K+YS+w7+1FVRklC+seAVUOLgVqEOn
         Y1MnNoG0/xpmbwPZjK5Rc6QDCUnyKEognILhf/z0/1KiC3sxEWA8y6mXEAOCUzhebJl3
         IOylAlP3wOEHmxoVKGEm5gHuF1GRN0Lge5U+oPvxl7pIZ9WGmcGu6vz2MV0TbiWJHRVo
         CERuXocR4reu3+ygu2lCaijsWa3RD7a/RDNiHnxEZO9F0Kfk1D5mHxTjeR7K6YPnHbsD
         +osg==
X-Gm-Message-State: AFqh2krPntG1zX6EJUczOsAD4Gnv3LSxmg9zHKPfORK5ypG902kTlN58
	F/2nLvIMqJBMkkjXViR8tRaURMOhY4+7ZBNvJezSgw==
X-Google-Smtp-Source: AMrXdXvYOrzkQmjMWSHWFzHn2KROc+9bR01AXt6Ip6abe59z2wbMGDfE0/JKvBAIipZawmQSBxW2beNWsvyiPJyIN+E=
X-Received: by 2002:a17:906:bcee:b0:84d:39d2:be19 with SMTP id
 op14-20020a170906bcee00b0084d39d2be19mr3976660ejb.363.1674611103158; Tue, 24
 Jan 2023 17:45:03 -0800 (PST)
MIME-Version: 1.0
References: <5e1916c6669ee2a918a2c22b7698e96f7dbf5488.1673568149.git.lisik@google.com>
 <CAKbZUD3z82Z4nP2PmfS-ED=_0UpGTRCnh4b7vw+RrRVKGCziTQ@mail.gmail.com>
In-Reply-To: <CAKbZUD3z82Z4nP2PmfS-ED=_0UpGTRCnh4b7vw+RrRVKGCziTQ@mail.gmail.com>
From: "Mikolaj Lisik" <lisik@google.com>
Date: Tue, 24 Jan 2023 17:44:51 -0800
Message-ID: <CADtC8PXzE8QjRzdR9NH-H=76qwhjQebq2RM4ddSTFBO9nRvcVQ@mail.gmail.com>
Subject: Re: [edk2-devel] [PATCH] OvmfPkg: Create additional PML4 entries for large SEV-SNP VMs
To: Pedro Falcato <pedro.falcato@gmail.com>
Cc: devel@edk2.groups.io, Erdem Aktas <erdemaktas@google.com>, 
	James Bottomley <jejb@linux.ibm.com>, "Yao, Jiewen" <jiewen.yao@intel.com>, Min Xu <min.m.xu@intel.com>, 
	Tom Lendacky <thomas.lendacky@amd.com>, michael.roth@amd.com
Content-Type: text/plain; charset="UTF-8"

Thanks for the review!

> Please swap the Present and ReadWrite lines. You should only set
> Present after everything else as to avoid explicit caching (TLB and
> paging structure) issues.
>
> Although this whole file is full of spotty behavior. ASSERTS can get
> deleted and the file is full of them.

Yes, keeping consistency with the rest of the file was my main
motivation for doing things this way. Will add popper error handling
bere in V2.

> There are plenty of Present = 1 sets before setting other important
> bits like RW, which *will* cause you to get bad TLB entries if the CPU
> speculates a load/store to that address.
...
> *sigh*
> In any case, because of that CpuFlushTlb () your patch isn't wrong,
> but it should be changed into something more MMU-code natural.

Makes sense! Thanks for all this information. Yes, I simply wanted to
order setting of the bits exactly as they have been done before in the
file. Will adjust in V2 and send a second patch adjusting them for
other instances.

Mikolaj