From: Norbert Manthey <nmanthey@amazon.de>
To: <xen-devel@lists.xenproject.org>
Cc: "Jan Beulich" <jbeulich@suse.com>,
"Andrew Cooper" <andrew.cooper3@citrix.com>,
"Roger Pau Monné" <roger.pau@citrix.com>, "Wei Liu" <wl@xen.org>,
"Norbert Manthey" <nmanthey@amazon.de>,
"Ian Jackson" <iwj@xenproject.org>
Subject: [PATCH HVM v2 1/1] hvm: refactor set param
Date: Fri, 5 Feb 2021 21:39:05 +0100 [thread overview]
Message-ID: <20210205203905.8824-1-nmanthey@amazon.de> (raw)
To prevent leaking HVM params via L1TF and similar issues on a
hyperthread pair, let's load values of domains as late as possible.
Furthermore, speculative barriers are re-arranged to make sure we do not
allow guests running on co-located VCPUs to leak hvm parameter values of
other domains.
This is part of the speculative hardening effort.
Signed-off-by: Norbert Manthey <nmanthey@amazon.de>
Reported-by: Hongyan Xia <hongyxia@amazon.co.uk>
---
v2: Add another speculative blocker, which protects the return code check
of the function hvm_allow_set_param.
xen/arch/x86/hvm/hvm.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4060,7 +4060,7 @@ static int hvm_allow_set_param(struct domain *d,
uint32_t index,
uint64_t new_value)
{
- uint64_t value = d->arch.hvm.params[index];
+ uint64_t value;
int rc;
rc = xsm_hvm_param(XSM_TARGET, d, HVMOP_set_param);
@@ -4108,6 +4108,13 @@ static int hvm_allow_set_param(struct domain *d,
if ( rc )
return rc;
+ if ( index >= HVM_NR_PARAMS )
+ return -EINVAL;
+
+ /* Make sure we evaluate permissions before loading data of domains. */
+ block_speculation();
+
+ value = d->arch.hvm.params[index];
switch ( index )
{
/* The following parameters should only be changed once. */
@@ -4141,6 +4148,9 @@ static int hvm_set_param(struct domain *d, uint32_t index, uint64_t value)
if ( rc )
return rc;
+ /* Make sure we evaluate permissions before loading data of domains. */
+ block_speculation();
+
switch ( index )
{
case HVM_PARAM_CALLBACK_IRQ:
@@ -4388,6 +4398,10 @@ int hvm_get_param(struct domain *d, uint32_t index, uint64_t *value)
if ( rc )
return rc;
+ /* Make sure the index bound check in hvm_get_param is respected, as well as
+ the above domain permissions. */
+ block_speculation();
+
switch ( index )
{
case HVM_PARAM_ACPI_S_STATE:
@@ -4428,9 +4442,6 @@ static int hvmop_get_param(
if ( a.index >= HVM_NR_PARAMS )
return -EINVAL;
- /* Make sure the above bound check is not bypassed during speculation. */
- block_speculation();
-
d = rcu_lock_domain_by_any_id(a.domid);
if ( d == NULL )
return -ESRCH;
--
2.17.1
Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879
next reply other threads:[~2021-02-05 20:39 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-05 20:39 Norbert Manthey [this message]
2021-02-08 14:21 ` [PATCH HVM v2 1/1] hvm: refactor set param Jan Beulich
2021-02-08 19:47 ` Norbert Manthey
2021-02-08 20:00 ` [PATCH HVM v3 " Norbert Manthey
2021-02-09 10:06 ` Jan Beulich
2021-02-09 9:40 ` [PATCH HVM v2 " Jan Beulich
2021-02-09 13:41 ` Norbert Manthey
2021-02-09 13:45 ` Jan Beulich
2021-02-09 13:56 ` Norbert Manthey
2021-02-09 14:21 ` Jan Beulich
2021-02-11 20:46 ` Norbert Manthey
2021-02-12 10:04 ` Jan Beulich
2021-02-12 12:28 ` Norbert Manthey
2021-02-18 15:01 ` [PATCH HVM v4 " Norbert Manthey
2021-02-19 13:44 ` Jan Beulich
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