Hi Paul,
On 9/26/19 11:03 AM, Paul Durrant wrote:
...when the IOMMU is not enabled.
80ff3d338dc9 "iommu: tidy up iommu_use_hap_pt() and need_iommu_pt_sync()
macros" introduced CONFIG_IOMMU_FORCE_PT_SHARE, which causes the global
'iommu_hap_pt_share' option to be replaced with a #define-d value of true.
In this configuration, calling clear_iommu_hap_pt_share() will result
trigger the aforementioned ASSERT.
CONFIG_IOMMU_FORCE_PT_SHARE is always selected for ARM builds and,
because clear_iommu_hap_pt_share() is called by the common iommu_setup()
function if the IOMMU is not enabled, it is no longer safe to disable the
IOMMU on ARM systems.
However, running with the IOMMU disabled is a valid configuration for ARM
systems, so this patch rectifies the problem by removing the call to
clear_iommu_hap_pt_share() from common code. As a side effect of this,
however, it becomes possible on x86 systems for iommu_enabled to be false
but iommu_hap_pt_share to be true. Thus the code in sysctl.c
needs to be changed to make sure that XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share
is not erroneously advertised when the IOMMU has been disabled.
Signed-off-by: Paul Durrant <paul.durr...@citrix.com>
Reported-by: Oleksandr <olekst...@gmail.com>
With one NIT below:
Acked-by: Julien Grall <julien.gr...@arm.com>
---
Cc: Andrew Cooper <andrew.coop...@citrix.com>
Cc: George Dunlap <george.dun...@eu.citrix.com>
Cc: Ian Jackson <ian.jack...@eu.citrix.com>
Cc: Jan Beulich <jbeul...@suse.com>
Cc: Julien Grall <julien.gr...@arm.com>
Cc: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
Cc: Stefano Stabellini <sstabell...@kernel.org>
Cc: Tim Deegan <t...@xen.org>
Cc: Wei Liu <w...@xen.org>
---
xen/common/sysctl.c | 6 ++++--
xen/drivers/passthrough/iommu.c | 1 -
2 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/xen/common/sysctl.c b/xen/common/sysctl.c
index e8763c7fdf..f88a285e7f 100644
--- a/xen/common/sysctl.c
+++ b/xen/common/sysctl.c
@@ -268,9 +268,11 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t)
u_sysctl)
pi->max_mfn = get_upper_mfn_bound();
arch_do_physinfo(pi);
if ( iommu_enabled )
+ {
pi->capabilities |= XEN_SYSCTL_PHYSCAP_directio;
- if ( iommu_hap_pt_share )
- pi->capabilities |= XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share;
+ if ( iommu_hap_pt_share )
+ pi->capabilities |= XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share;
+ }
if ( copy_to_guest(u_sysctl, op, 1) )
ret = -EFAULT;
diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index e8fddc2dc7..c33ca70ec9 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -456,7 +456,6 @@ int __init iommu_setup(void)
if ( !iommu_enabled )
{
iommu_intremap = 0;
- clear_iommu_hap_pt_share();
}
NIT: The {} can now be removed.
I can fix it on commit.
Cheers,
--
Julien Grall
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