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mmu-hash*: Don't update PTE flags when permission is denied 

BEHAVIOUR CHANGE

Currently if ppc_hash{32,64}_translate() finds a PTE matching the given
virtual address, it will always update the PTE's R & C (Referenced and
Changed) bits.  This happens even if the PTE's permissions mean we are
about to deny the translation.

This is clearly a bug, although we get away with it because:
  a) It will only incorrectly set, never reset the bits, which should not
cause guest correctness problems.
  b) Linux guests never use the R & C bits anyway.

This patch fixes the behaviour, only updating R & C when access is granted
by the PTE.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
David Gibson 2013-03-12 00:31:38 +00:00 committed by Alexander Graf
parent 59acbe2855
commit 87dc3fd13e
2 changed files with 14 additions and 10 deletions
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12
target-ppc/mmu-hash32.c
View File

@ -439,15 +439,17 @@ static int ppc_hash32_translate(CPUPPCState *env, struct mmu_ctx_hash32 *ctx,
ctx->raddr = pte.pte1;
ctx->prot = access;
ret = ppc_hash32_check_prot(ctx->prot, rwx);
if (ret == 0) {
/* Access granted */
LOG_MMU("PTE access granted !\n");
} else {
if (ret) {
/* Access right violation */
LOG_MMU("PTE access rejected\n");
return ret;
}
/* Update page flags */
LOG_MMU("PTE access granted !\n");
/* 8. Update PTE referenced and changed bits if necessary */
if (ppc_hash32_pte_update_flags(ctx, &pte.pte1, ret, rwx) == 1) {
ppc_hash32_store_hpte1(env, pte_offset, pte.pte1);
}

12
target-ppc/mmu-hash64.c
View File

@ -460,15 +460,17 @@ static int ppc_hash64_translate(CPUPPCState *env, struct mmu_ctx_hash64 *ctx,
ctx->raddr = pte.pte1;
ctx->prot = access;
ret = ppc_hash64_check_prot(ctx->prot, rwx);
if (ret == 0) {
/* Access granted */
LOG_MMU("PTE access granted !\n");
} else {
if (ret) {
/* Access right violation */
LOG_MMU("PTE access rejected\n");
return ret;
}
/* Update page flags */
LOG_MMU("PTE access granted !\n");
/* 6. Update PTE referenced and changed bits if necessary */
if (ppc_hash64_pte_update_flags(ctx, &pte.pte1, ret, rwx) == 1) {
ppc_hash64_store_hpte1(env, pte_offset, pte.pte1);
}