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target/ppc: Yet another fix for KVM-HV HPTE accessors 

As stated in the 1ad9f0a464 commit log, the returned entries are not
a whole PTEG. It was not a problem before 1ad9f0a464 as it would read
a single record assuming it contains a whole PTEG but now the code tries
reading the entire PTEG and "if ((n - i) < invalid)" produces negative
values which then are converted to size_t for memset() and that throws
seg fault.

This fixes the math.

While here, fix the last @i increment as well.

Fixes: 1ad9f0a464 "target/ppc: Fix KVM-HV HPTE accessors"
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Alexey Kardashevskiy 2018-01-11 15:08:32 +11:00 committed by David Gibson
parent 8e5dc9ba49
commit a36593e167
1 changed files with 7 additions and 4 deletions
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11
target/ppc/kvm.c
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@ -2667,21 +2667,24 @@ void kvmppc_read_hptes(ppc_hash_pte64_t *hptes, hwaddr ptex, int n)
hdr = (struct kvm_get_htab_header *)buf;
while ((i < n) && ((char *)hdr < (buf + rc))) {
int invalid = hdr->n_invalid;
int invalid = hdr->n_invalid, valid = hdr->n_valid;
if (hdr->index != (ptex + i)) {
hw_error("kvmppc_read_hptes: Unexpected HPTE index %"PRIu32
" != (%"HWADDR_PRIu" + %d", hdr->index, ptex, i);
}
memcpy(hptes + i, hdr + 1, HASH_PTE_SIZE_64 * hdr->n_valid);
i += hdr->n_valid;
if (n - i < valid) {
valid = n - i;
}
memcpy(hptes + i, hdr + 1, HASH_PTE_SIZE_64 * valid);
i += valid;
if ((n - i) < invalid) {
invalid = n - i;
}
memset(hptes + i, 0, invalid * HASH_PTE_SIZE_64);
i += hdr->n_invalid;
i += invalid;
hdr = (struct kvm_get_htab_header *)
((char *)(hdr + 1) + HASH_PTE_SIZE_64 * hdr->n_valid);