[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH HVM v1 1/1] hvm: refactor set param
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@xxxxxxxxx> Reported-by: Hongyan Xia <hongyxia@xxxxxxxxxxxx> --- xen/arch/x86/hvm/hvm.c | 16 ++++++++++++---- 1 file changed, 12 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_domain.params[index]; switch ( index ) { /* The following parameters should only be changed once. */ @@ -4388,6 +4395,10 @@ 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 +4439,6 @@ 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
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