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| author | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2019-02-15 18:00:23 +0100 |
|---|---|---|
| committer | David Gibson <david@gibson.dropbear.id.au> | 2019-02-26 09:21:25 +1100 |
| commit | 3054b0ca4bdd83e0780bd76805ca17aa733031c8 (patch) | |
| tree | 9f53c5e901a52ca745dfc2ae28d9de8668188122 /target | |
| parent | 2819282dae6c38b2c9d5499ad748b1471f26af1a (diff) | |
| download | qemu-3054b0ca4bdd83e0780bd76805ca17aa733031c8.zip qemu-3054b0ca4bdd83e0780bd76805ca17aa733031c8.tar.gz qemu-3054b0ca4bdd83e0780bd76805ca17aa733031c8.tar.bz2 | |
target/ppc: Fix ordering of hash MMU accesses
With mttcg, we can have MMU lookups happening at the same time
as the guest modifying the page tables.
Since the HPTEs of the hash table MMU contains two words (or
double worlds on 64-bit), we need to make sure we read them
in the right order, with the correct memory barrier.
Additionally, when using emulated SPAPR mode, the hypercalls
writing to the hash table must also perform the udpates in
the right order.
Note: This part is still not entirely correct
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20190215170029.15641-7-clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Diffstat (limited to 'target')
| -rw-r--r-- | target/ppc/mmu-hash32.c | 6 | ||||
| -rw-r--r-- | target/ppc/mmu-hash64.c | 6 |
2 files changed, 12 insertions, 0 deletions
diff --git a/target/ppc/mmu-hash32.c b/target/ppc/mmu-hash32.c index 03ae3c1..e8562a7 100644 --- a/target/ppc/mmu-hash32.c +++ b/target/ppc/mmu-hash32.c @@ -319,6 +319,12 @@ static hwaddr ppc_hash32_pteg_search(PowerPCCPU *cpu, hwaddr pteg_off, for (i = 0; i < HPTES_PER_GROUP; i++) { pte0 = ppc_hash32_load_hpte0(cpu, pte_offset); + /* + * pte0 contains the valid bit and must be read before pte1, + * otherwise we might see an old pte1 with a new valid bit and + * thus an inconsistent hpte value + */ + smp_rmb(); pte1 = ppc_hash32_load_hpte1(cpu, pte_offset); if ((pte0 & HPTE32_V_VALID) diff --git a/target/ppc/mmu-hash64.c b/target/ppc/mmu-hash64.c index 1175b99..fbefe5b 100644 --- a/target/ppc/mmu-hash64.c +++ b/target/ppc/mmu-hash64.c @@ -507,6 +507,12 @@ static hwaddr ppc_hash64_pteg_search(PowerPCCPU *cpu, hwaddr hash, } for (i = 0; i < HPTES_PER_GROUP; i++) { pte0 = ppc_hash64_hpte0(cpu, pteg, i); + /* + * pte0 contains the valid bit and must be read before pte1, + * otherwise we might see an old pte1 with a new valid bit and + * thus an inconsistent hpte value + */ + smp_rmb(); pte1 = ppc_hash64_hpte1(cpu, pteg, i); /* This compares V, B, H (secondary) and the AVPN */ |