From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:44416) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UFMVZ-0000Ke-JZ for qemu-devel@nongnu.org; Tue, 12 Mar 2013 06:33:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UFMV7-0004o3-0M for qemu-devel@nongnu.org; Tue, 12 Mar 2013 06:32:37 -0400 From: David Gibson Date: Tue, 12 Mar 2013 21:31:38 +1100 Message-Id: <1363084310-4115-37-git-send-email-david@gibson.dropbear.id.au> In-Reply-To: <1363084310-4115-1-git-send-email-david@gibson.dropbear.id.au> References: <1363084310-4115-1-git-send-email-david@gibson.dropbear.id.au> Subject: [Qemu-devel] [PATCH 36/48] mmu-hash*: Don't update PTE flags when permission is denied List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: agraf@suse.de Cc: David Gibson , qemu-ppc@nongnu.org, afaerber@suse.de, qemu-devel@nongnu.org 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 --- target-ppc/mmu-hash32.c | 12 +++++++----- target-ppc/mmu-hash64.c | 12 +++++++----- 2 files changed, 14 insertions(+), 10 deletions(-) diff --git a/target-ppc/mmu-hash32.c b/target-ppc/mmu-hash32.c index 3488092..ae606fd 100644 --- a/target-ppc/mmu-hash32.c +++ b/target-ppc/mmu-hash32.c @@ -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); } diff --git a/target-ppc/mmu-hash64.c b/target-ppc/mmu-hash64.c index 2e109f4..f7aa352 100644 --- a/target-ppc/mmu-hash64.c +++ b/target-ppc/mmu-hash64.c @@ -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); } -- 1.7.10.4