From 93de2a6a4b91b72607136dd656edf03fb399d27f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 23 Sep 2026 09:37:21 -0700 Subject: KVM: SEV: Do cache maintenance on the source VM during intra-host migration 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 Signed-off-by: Sean Christopherson Message-ID: <20260923163721.1584779-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- scripts/coccinelle/api/kvmalloc.cocci | 256 ++++++++++++++++++++++++++++++++++ 1 file changed, 256 insertions(+) create mode 100644 scripts/coccinelle/api/kvmalloc.cocci (limited to 'scripts/coccinelle/api/kvmalloc.cocci') diff --git a/scripts/coccinelle/api/kvmalloc.cocci b/scripts/coccinelle/api/kvmalloc.cocci new file mode 100644 index 000000000..5ddcb76b7 --- /dev/null +++ b/scripts/coccinelle/api/kvmalloc.cocci @@ -0,0 +1,256 @@ +// SPDX-License-Identifier: GPL-2.0-only +/// +/// Find if/else condition with kmalloc/vmalloc calls. +/// Suggest to use kvmalloc instead. Same for kvfree. +/// +// Confidence: High +// Copyright: (C) 2020 Denis Efremov ISPRAS +// Options: --no-includes --include-headers +// + +virtual patch +virtual report +virtual org +virtual context + +@initialize:python@ +@@ +filter = frozenset(['kvfree']) + +def relevant(p): + return not (filter & {el.current_element for el in p}) + +@kvmalloc depends on !patch@ +expression E, E1, size; +identifier flags; +binary operator cmp = {<=, <, ==, >, >=}; +identifier x; +type T; +position p; +@@ + +( +* if (size cmp E1 || ...)@p { + ... +* E = \(kmalloc\|kzalloc\|kcalloc\|kmalloc_node\|kzalloc_node\| +* kmalloc_array\|kmalloc_array_node\|kcalloc_node\) +* (..., size, \(flags\|GFP_KERNEL\|\(GFP_KERNEL\|flags\)|__GFP_NOWARN\), ...) + ... + } else { + ... +* E = \(vmalloc\|vzalloc\|vmalloc_node\|vzalloc_node\)(..., size, ...) + ... + } +| +* E = \(kmalloc\|kzalloc\|kcalloc\|kmalloc_node\|kzalloc_node\| +* kmalloc_array\|kmalloc_array_node\|kcalloc_node\) +* (..., size, \(flags\|GFP_KERNEL\|\(GFP_KERNEL\|flags\)|__GFP_NOWARN\), ...) + ... when != E = E1 + when != size = E1 + when any +* if (E == NULL)@p { + ... +* E = \(vmalloc\|vzalloc\|vmalloc_node\|vzalloc_node\)(..., size, ...) + ... + } +| +* T x = \(kmalloc\|kzalloc\|kcalloc\|kmalloc_node\|kzalloc_node\| +* kmalloc_array\|kmalloc_array_node\|kcalloc_node\) +* (..., size, \(flags\|GFP_KERNEL\|\(GFP_KERNEL\|flags\)|__GFP_NOWARN\), ...); + ... when != x = E1 + when != size = E1 + when any +* if (x == NULL)@p { + ... +* x = \(vmalloc\|vzalloc\|vmalloc_node\|vzalloc_node\)(..., size, ...) + ... + } +) + +@kvfree depends on !patch@ +expression E; +position p : script:python() { relevant(p) }; +@@ + +* if (is_vmalloc_addr(E))@p { + ... +* vfree(E) + ... + } else { + ... when != krealloc(E, ...) + when any +* \(kfree\|kfree_sensitive\)(E) + ... + } + +@depends on patch@ +expression E, E1, size, node; +binary operator cmp = {<=, <, ==, >, >=}; +identifier flags, x; +type T; +@@ + +( +- if (size cmp E1) +- E = kmalloc(size, flags); +- else +- E = vmalloc(size); ++ E = kvmalloc(size, flags); +| +- if (size cmp E1) +- E = kmalloc(size, \(GFP_KERNEL\|GFP_KERNEL|__GFP_NOWARN\)); +- else +- E = vmalloc(size); ++ E = kvmalloc(size, GFP_KERNEL); +| +- E = kmalloc(size, flags | __GFP_NOWARN); +- if (E == NULL) +- E = vmalloc(size); ++ E = kvmalloc(size, flags); +| +- E = kmalloc(size, \(GFP_KERNEL\|GFP_KERNEL|__GFP_NOWARN\)); +- if (E == NULL) +- E = vmalloc(size); ++ E = kvmalloc(size, GFP_KERNEL); +| +- T x = kmalloc(size, flags | __GFP_NOWARN); +- if (x == NULL) +- x = vmalloc(size); ++ T x = kvmalloc(size, flags); +| +- T x = kmalloc(size, \(GFP_KERNEL\|GFP_KERNEL|__GFP_NOWARN\)); +- if (x == NULL) +- x = vmalloc(size); ++ T x = kvmalloc(size, GFP_KERNEL); +| +- if (size cmp E1) +- E = kzalloc(size, flags); +- else +- E = vzalloc(size); ++ E = kvzalloc(size, flags); +| +- if (size cmp E1) +- E = kzalloc(size, \(GFP_KERNEL\|GFP_KERNEL|__GFP_NOWARN\)); +- else +- E = vzalloc(size); ++ E = kvzalloc(size, GFP_KERNEL); +| +- E = kzalloc(size, flags | __GFP_NOWARN); +- if (E == NULL) +- E = vzalloc(size); ++ E = kvzalloc(size, flags); +| +- E = kzalloc(size, \(GFP_KERNEL\|GFP_KERNEL|__GFP_NOWARN\)); +- if (E == NULL) +- E = vzalloc(size); ++ E = kvzalloc(size, GFP_KERNEL); +| +- T x = kzalloc(size, flags | __GFP_NOWARN); +- if (x == NULL) +- x = vzalloc(size); ++ T x = kvzalloc(size, flags); +| +- T x = kzalloc(size, \(GFP_KERNEL\|GFP_KERNEL|__GFP_NOWARN\)); +- if (x == NULL) +- x = vzalloc(size); ++ T x = kvzalloc(size, GFP_KERNEL); +| +- if (size cmp E1) +- E = kmalloc_node(size, flags, node); +- else +- E = vmalloc_node(size, node); ++ E = kvmalloc_node(size, flags, node); +| +- if (size cmp E1) +- E = kmalloc_node(size, \(GFP_KERNEL\|GFP_KERNEL|__GFP_NOWARN\), node); +- else +- E = vmalloc_node(size, node); ++ E = kvmalloc_node(size, GFP_KERNEL, node); +| +- E = kmalloc_node(size, flags | __GFP_NOWARN, node); +- if (E == NULL) +- E = vmalloc_node(size, node); ++ E = kvmalloc_node(size, flags, node); +| +- E = kmalloc_node(size, \(GFP_KERNEL\|GFP_KERNEL|__GFP_NOWARN\), node); +- if (E == NULL) +- E = vmalloc_node(size, node); ++ E = kvmalloc_node(size, GFP_KERNEL, node); +| +- T x = kmalloc_node(size, flags | __GFP_NOWARN, node); +- if (x == NULL) +- x = vmalloc_node(size, node); ++ T x = kvmalloc_node(size, flags, node); +| +- T x = kmalloc_node(size, \(GFP_KERNEL\|GFP_KERNEL|__GFP_NOWARN\), node); +- if (x == NULL) +- x = vmalloc_node(size, node); ++ T x = kvmalloc_node(size, GFP_KERNEL, node); +| +- if (size cmp E1) +- E = kvzalloc_node(size, flags, node); +- else +- E = vzalloc_node(size, node); ++ E = kvzalloc_node(size, flags, node); +| +- if (size cmp E1) +- E = kvzalloc_node(size, \(GFP_KERNEL\|GFP_KERNEL|__GFP_NOWARN\), node); +- else +- E = vzalloc_node(size, node); ++ E = kvzalloc_node(size, GFP_KERNEL, node); +| +- E = kvzalloc_node(size, flags | __GFP_NOWARN, node); +- if (E == NULL) +- E = vzalloc_node(size, node); ++ E = kvzalloc_node(size, flags, node); +| +- E = kvzalloc_node(size, \(GFP_KERNEL\|GFP_KERNEL|__GFP_NOWARN\), node); +- if (E == NULL) +- E = vzalloc_node(size, node); ++ E = kvzalloc_node(size, GFP_KERNEL, node); +| +- T x = kvzalloc_node(size, flags | __GFP_NOWARN, node); +- if (x == NULL) +- x = vzalloc_node(size, node); ++ T x = kvzalloc_node(size, flags, node); +| +- T x = kvzalloc_node(size, \(GFP_KERNEL\|GFP_KERNEL|__GFP_NOWARN\), node); +- if (x == NULL) +- x = vzalloc_node(size, node); ++ T x = kvzalloc_node(size, GFP_KERNEL, node); +) + +@depends on patch@ +expression E; +position p : script:python() { relevant(p) }; +@@ + +- if (is_vmalloc_addr(E))@p +- vfree(E); +- else +- kfree(E); ++ kvfree(E); + +@script: python depends on report@ +p << kvmalloc.p; +@@ + +coccilib.report.print_report(p[0], "WARNING opportunity for kvmalloc") + +@script: python depends on org@ +p << kvmalloc.p; +@@ + +coccilib.org.print_todo(p[0], "WARNING opportunity for kvmalloc") + +@script: python depends on report@ +p << kvfree.p; +@@ + +coccilib.report.print_report(p[0], "WARNING opportunity for kvfree") + +@script: python depends on org@ +p << kvfree.p; +@@ + +coccilib.org.print_todo(p[0], "WARNING opportunity for kvfree") -- cgit v1.3.1