On 10/6/25 2:25 AM, Sairaj Kodilkar wrote:
On 10/6/2025 11:45 AM, Michael S. Tsirkin wrote:
On Mon, Oct 06, 2025 at 11:38:28AM +0530, Sairaj Kodilkar wrote:
On 9/20/2025 3:05 AM, Alejandro Jimenez wrote:
A guest must issue an INVALIDATE_DEVTAB_ENTRY command after changing a
Device Table entry (DTE) e.g. after attaching a device and setting
up its
DTE. When intercepting this event, determine if the DTE has been
configured
for paging or not, and toggle the appropriate memory regions to
allow DMA
address translation for the address space if needed. Requires
dma-remap=on.
Signed-off-by: Alejandro Jimenez <[email protected]>
---
hw/i386/amd_iommu.c | 122
+++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 120 insertions(+), 2 deletions(-)
diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c
index ce5d4c36624fd..e916dcb2be381 100644
--- a/hw/i386/amd_iommu.c
+++ b/hw/i386/amd_iommu.c
@@ -1032,18 +1032,136 @@ static void
amdvi_reset_address_translation_all(AMDVIState *s)
}
}
+static void enable_dma_mode(AMDVIAddressSpace *as, bool
inval_current)
+{
+ /*
+ * When enabling DMA mode for the purpose of isolating guest
devices on
+ * a failure to retrieve or invalid DTE, all existing mappings
must be
+ * dropped.
+ */
+ if (inval_current) {
+ IOMMUNotifier *n;
+ IOMMU_NOTIFIER_FOREACH(n, &as->iommu) {
+ amdvi_address_space_unmap(as, n);
+ }
+ }
+
+ if (as->addr_translation) {
+ return;
+ }
+
+ /* Installing DTE enabling translation, activate region */
+ as->addr_translation = true;
+ amdvi_switch_address_space(as);
+ /* Sync shadow page tables */
+ amdvi_address_space_sync(as);
Hi Alejandro,
I think we can skip amdvi_address_space_sync, because
amdvi_switch_address_space will trigger
amdvi_iommu_replay. this replay should unmap all the old mappings
and sync
shadow page table.
Thanks
Sairaj
Well I queued this but this speedup can be done on top.
ACK
I rather be explicit and avoid relying on replay(), but sync is
expensive so this could be worth the trouble with an added comment. I'll
test and will include Sairaj's optimization in a different patchset.
Please if possible also add Sairaj's R-b to this series, he provided
valuable feedback and testing so I'd like it to be recognized.
Alejandro
Sorry for the delay in reviewing, I was on vacation for 2 weeks.
I have reviewed all the patches.
Reviewed-by: Sairaj Kodilkar <[email protected]>Thanks Sairaj
