KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

Manually perform cache maintenance on the source VM during intra-host
migration to ensure no stale data is left in CPU caches after the VM is
destroyed.  Because the source VM is "converted" to a non-SEV VM, KVM's
memory reclaim flows won't trigger cache maintenance, e.g. when all guest
memory is reclaimed in response to detaching from the mmu_notifier.

Note, relying on the destination VM to do cache maintenance isn't an option
as KVM doesn't require identical guest memory configurations, i.e. the
source VM may have access to memory that the destination VM does not.
Enforcing equivalent memory configurations is infeasible, as it would
require a *deep* comparison of memslots, e.g. to verify that not only are
the memslot identical, but what the memslots point at is also identical.

Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration")
Cc: stable@vger.kernel.org
Reported-by: Stefan Teodorescu <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 360 insertions, 0 deletions

diff --git a/Documentation/sphinx-static/custom.css b/Documentation/sphinx-static/custom.css
new file mode 100644
index 000000000..6c03dca44
--- /dev/null
+++ b/Documentation/sphinx-static/custom.css
@@ -0,0 +1,203 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * CSS tweaks for the Alabaster theme
+ */
+
+div.body {  max-width: 120em; }
+
+/* Shrink the headers a bit */
+div.body h1 { font-size: 180%; }
+div.body h2 { font-size: 150%; }
+div.body h3 { font-size: 130%; }
+div.body h4 { font-size: 110%; }
+
+/* toctree captions are styled like h2 */
+div.toctree-wrapper p.caption[role=heading] { font-size: 150%; }
+
+/* Tighten up the layout slightly */
+div.body { padding: 0 15px 0 10px; }
+div.sphinxsidebarwrapper { padding: 1em 0.4em; }
+div.sphinxsidebar { font-size: inherit;
+		    max-height: 100%;
+		    overflow-y: auto; }
+/* Tweak document margins and don't force width */
+div.document {
+    margin: 20px 10px 0 10px;
+    width: auto;
+}
+
+/* Size the logo appropriately */
+img.logo {
+    width: 104px;
+    margin-bottom: 20px;
+}
+
+/* The default is to use -1em, which makes it override text */
+li { text-indent: 0em; }
+
+/*
+ * Parameters for the display of function prototypes and such included
+ * from C source files.
+ */
+dl.function, dl.struct, dl.enum { margin-top: 2em; background-color: #ecf0f3; }
+/* indent lines 2+ of multi-line function prototypes */
+dl.function dt { margin-left: 10em; text-indent: -10em; }
+/*
+ * Preserve C API signatures on one line and apply contained horizontal
+ * scrolling to prevent them from exceeding their container width and
+ * breaking page layout.
+ */
+dl.c { overflow-x: auto; overflow-y: hidden; }
+dl.c > dt.sig.sig-object { white-space: nowrap; }
+dt.sig-object { font-size: larger; }
+div.kernelindent { margin-left: 2em; margin-right: 4em; }
+
+/*
+ * Parameters for the display of function prototypes and such included
+ * from Python source files.
+ */
+dl.py { margin-top: 2em; background-color: #ecf0f3; }
+dl.py.class { margin-left: 2em; text-indent: -2em; padding-left: 2em; }
+dl.py.method, dl.py.attribute { margin-left: 2em; text-indent: -2em; }
+dl.py li, pre { text-indent: 0em; padding-left: 0 !important; }
+
+/*
+ * Tweaks for our local TOC
+ */
+div.kerneltoc li.toctree-l1 { font-size: smaller;
+		text-indent: -1em;
+		margin-left: 1em; }
+div.kerneltoc li.current > a {font-weight: bold; }
+div.kerneltoc li.toctree-l2,li.toctree-l3 { font-size: small;
+		text-indent: -1em;
+		margin-left: 1em;
+		list-style-type: none;
+	      }
+div.kerneltoc li.current ul { margin-left: 0; }
+div.kerneltoc { background-color: #eeeeee; }
+div.kerneltoc li.current ul { background-color: white; }
+
+/*
+ * Hide toctree captions on the welcome page, they should only be shown in the
+ * sidebar.
+ */
+section#the-linux-kernel-documentation p.caption { display: none; }
+
+/*
+ * Make section titles bold in the sidebar, and decrease their bottom margin to
+ * group them with their subsections.
+ */
+div.sphinxsidebar p.caption { font-weight: bold; margin-bottom: 0; }
+div.sphinxsidebar p.caption + ul { margin-top: 0; }
+
+/*
+ * The CSS magic to toggle the contents on small screens.
+ */
+label.kernel-toc-title { display: none; }
+label.kernel-toc-title:after {
+    content: "[Hide]";
+}
+input[type=checkbox]:checked ~ label.kernel-toc-title:after {
+    content: "[Show]";
+}
+/* Hide the toggle on large screens */
+input.kernel-toc-toggle { display: none; }
+
+/*
+ * Show and implement the toggle on small screens.
+ * The 875px width seems to be wired into alabaster.
+ */
+@media screen and (max-width: 875px) {
+    label.kernel-toc-title { display: inline;
+			     font-weight: bold;
+			     font-size: larger; }
+    input[type=checkbox]:checked ~ div.kerneltoc {
+	display: none;
+    }
+    h3.kernel-toc-contents { display: inline; }
+    div.kerneltoc a { color: black; }
+}
+
+/* Language selection menu */
+
+div.admonition {
+    /*
+     * Make sure we don't overlap notes and warnings at the top of the
+     * document.
+     */
+    clear: both;
+}
+
+div.language-selection {
+    background: #eeeeee;
+    border: 1px solid #cccccc;
+    margin-bottom: 1em;
+    padding: .5em;
+
+    position: relative;
+    float: right;
+}
+
+div.language-selection a {
+    display: block;
+    padding: 0.5em;
+    color: #333333;
+    text-decoration: none;
+}
+
+div.language-selection ul {
+    display: none;
+    position: absolute;
+
+    /* Align with the parent div */
+    top: 100%;
+    right: 0;
+    margin: 0;
+
+    list-style: none;
+
+    background: #fafafa;
+    border: 1px solid #cccccc;
+
+    /* Never break menu item lines */
+    white-space: nowrap;
+}
+
+div.language-selection:hover ul {
+    display: block;
+}
+
+div.language-selection ul li:hover {
+    background: #dddddd;
+}
+
+/* Let rendered reference links in tables wrap when needed. */
+div.body table.docutils a.reference {
+    overflow-wrap: anywhere;
+}
+
+/* Let long link text wrap instead of forcing overflow. */
+a {
+    overflow-wrap: anywhere;
+}
+
+/* Make xrefs more universally visible */
+a.reference, a.reference:hover {
+    border-bottom: none;
+    text-decoration: underline;
+    text-underline-offset: 0.3em;
+}
+
+/* Slightly different style for sidebar links */
+div.sphinxsidebar a { border-bottom: none; }
+div.sphinxsidebar a:hover {
+    border-bottom: none;
+    text-decoration: underline;
+    text-underline-offset: 0.3em;
+}
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+a.manpage {
+	font-style: normal;
+	font-weight: bold;
+	font-family: "Courier New", Courier, monospace;
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diff --git a/Documentation/sphinx-static/theme_overrides.css b/Documentation/sphinx-static/theme_overrides.css
new file mode 100644
index 000000000..79000b26e
--- /dev/null
+++ b/Documentation/sphinx-static/theme_overrides.css
@@ -0,0 +1,120 @@
+/* -*- coding: utf-8; mode: css -*-
+ *
+ * Sphinx HTML theme customization: read the doc
+ * Please don't add any color definition here, as the theme should
+ * work for both normal and dark modes.
+ */
+
+/* Improve contrast and increase size for easier reading. */
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+body {
+	font-family: serif;
+	font-size: 100%;
+}
+
+h1, h2, .rst-content .toctree-wrapper p.caption, h3, h4, h5, h6, legend {
+	font-family: sans-serif;
+}
+
+div[class^="highlight"] pre {
+	font-family: monospace;
+	font-size: 100%;
+}
+
+.wy-menu-vertical {
+	font-family: sans-serif;
+}
+
+.c {
+	font-style: normal;
+}
+
+p {
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+}
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+/* Interim: Code-blocks with line nos - lines and line numbers don't line up.
+ * see: https://github.com/rtfd/sphinx_rtd_theme/issues/419
+ */
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+div[class^="highlight"] pre {
+    line-height: normal;
+}
+.rst-content .highlight > pre {
+    line-height: normal;
+}
+
+/* Keep fields from being strangely far apart due to inheirited table CSS. */
+.rst-content table.field-list th.field-name {
+    padding-top: 1px;
+    padding-bottom: 1px;
+}
+.rst-content table.field-list td.field-body {
+    padding-top: 1px;
+    padding-bottom: 1px;
+}
+
+@media screen {
+
+    /* content column
+     *
+     * RTD theme's default is 800px as max width for the content, but we have
+     * tables with tons of columns, which need the full width of the view-port.
+     */
+
+    .wy-nav-content{max-width: none; }
+
+    /* table:
+     *
+     *   - Sequences of whitespace should collapse into a single whitespace.
+     *   - make the overflow auto (scrollbar if needed)
+     *   - align caption "left" ("center" is unsuitable on vast tables)
+     */
+
+    .wy-table-responsive table td { white-space: normal; }
+    .wy-table-responsive { overflow: auto; }
+    .rst-content table.docutils caption { text-align: left; font-size: 100%; }
+
+    /* captions:
+     *
+     *   - captions should have 100% (not 85%) font size
+     *   - hide the permalink symbol as long as link is not hovered
+     */
+
+    caption, .wy-table caption, .rst-content table.field-list caption {
+        font-size: 100%;
+    }
+    caption a.headerlink { opacity: 0; }
+    caption a.headerlink:hover { opacity: 1; }
+
+    /* Menu selection and keystrokes */
+
+    span.menuselection {
+	font-family: "Courier New", Courier, monospace
+    }
+
+    code.kbd, code.kbd span {
+	font-weight: bold;
+	font-family: "Courier New", Courier, monospace
+    }
+
+    /* fix bottom margin of lists items */
+
+    .rst-content .section ul li:last-child, .rst-content .section ul li p:last-child {
+          margin-bottom: 12px;
+    }
+
+    /* inline literal: drop the borderbox, padding and red color */
+
+    code, .rst-content tt, .rst-content code {
+        color: inherit;
+        border: none;
+        padding: unset;
+        background: inherit;
+        font-size: 85%;
+    }
+
+    .rst-content tt.literal,.rst-content tt.literal,.rst-content code.literal {
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+}
diff --git a/Documentation/sphinx-static/theme_rtd_colors.css b/Documentation/sphinx-static/theme_rtd_colors.css
new file mode 100644
index 000000000..55b6e1c36
--- /dev/null
+++ b/Documentation/sphinx-static/theme_rtd_colors.css
@@ -0,0 +1,37 @@
+/* -*- coding: utf-8; mode: css -*-
+ *
+ * Sphinx HTML theme customization: color settings for RTD (non-dark) theme
+ *
+ */
+
+/* Improve contrast and increase size for easier reading. */
+
+body {
+	color: black;
+}
+
+.wy-menu-vertical li.current a {
+	color: #505050;
+}
+
+.wy-menu-vertical li.on a, .wy-menu-vertical li.current > a {
+	color: #303030;
+}
+
+div[class^="highlight"] pre {
+	color: black;
+}
+
+@media screen {
+
+    /* Menu selection and keystrokes */
+
+    span.menuselection {
+	color: blue;
+    }
+
+    code.kbd, code.kbd span {
+	color: white;
+	background-color: darkblue;
+    }
+}