Hello Giacomo Travaglini,
I'd like you to do a code review. Please visit
https://gem5-review.googlesource.com/10505
to review the following change.
Change subject: arch-arm: Fix page size handling when merging stage 1 and 2
......................................................................
arch-arm: Fix page size handling when merging stage 1 and 2
The current code to merge translation entries from stage 1 and stage 2
doesn't handle cases where the page sizes at the different stages
differ. This change fixes both the case when the hypervisor has a
larger page size and when it has a smaller page size.
Change-Id: Icdf289005bf1e4de4d91d54643924a38d9d77796
Signed-off-by: Andreas Sandberg <[email protected]>
Reviewed-by: Giacomo Travaglini <[email protected]>
---
M src/arch/arm/stage2_lookup.cc
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/src/arch/arm/stage2_lookup.cc b/src/arch/arm/stage2_lookup.cc
index 82a29e8..00c515d 100644
--- a/src/arch/arm/stage2_lookup.cc
+++ b/src/arch/arm/stage2_lookup.cc
@@ -88,23 +88,24 @@
// Now we have the table entries for both stages of translation
// merge them and insert the result into the stage 1 TLB. See
// CombineS1S2Desc() in pseudocode
- stage1Te.N = stage2Te->N;
stage1Te.nonCacheable |= stage2Te->nonCacheable;
stage1Te.xn |= stage2Te->xn;
if (stage1Te.size > stage2Te->size) {
// Size mismatch also implies vpn mismatch (this is shifted by
// sizebits!).
- stage1Te.vpn = s1Req->getVaddr() / (stage2Te->size+1);
+ stage1Te.vpn = s1Req->getVaddr() >> stage2Te->N;
stage1Te.pfn = stage2Te->pfn;
stage1Te.size = stage2Te->size;
+ stage1Te.N = stage2Te->N;
} else if (stage1Te.size < stage2Te->size) {
// Guest 4K could well be section-backed by host hugepage! In
this
// case a 4K entry is added but pfn needs to be adjusted. New
PFN =
// offset into section PFN given by stage2 IPA treated as a
stage1
// page size.
- stage1Te.pfn = (stage2Te->pfn * ((stage2Te->size+1) /
(stage1Te.size+1))) +
- (stage2Te->vpn / (stage1Te.size+1));
+ const Addr pa = (stage2Te->pfn << stage2Te->N);
+ const Addr ipa = (stage1Te.pfn << stage1Te.N);
+ stage1Te.pfn = (pa | (ipa & mask(stage2Te->N))) >> stage1Te.N;
// Size remains smaller of the two.
} else {
// Matching sizes
--
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Gerrit-Project: public/gem5
Gerrit-Branch: master
Gerrit-Change-Id: Icdf289005bf1e4de4d91d54643924a38d9d77796
Gerrit-Change-Number: 10505
Gerrit-PatchSet: 1
Gerrit-Owner: Andreas Sandberg <[email protected]>
Gerrit-Reviewer: Giacomo Travaglini <[email protected]>
Gerrit-MessageType: newchange
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