On Fri, Nov 26, 2021 at 04:39:40PM -0300, Leandro Lupori wrote:
> When updating the R bit of a PTE, the Hash64 MMU was using a wrong byte
> offset, causing the first byte of the adjacent PTE to be corrupted.
> This caused a panic when booting FreeBSD, using the Hash MMU.
>
> Fixes: a2dd4e83e76b ("ppc/hash64: Rework R and C bit updates")
> Signed-off-by: Leandro Lupori <leandro.lup...@eldorado.org.br>
> ---
> Changes from v2:
> - Add new defines for the byte offset of PTE bit C and
> HASH_PTE_SIZE_64 / 2 (pte1)
> - Use new defines in hash64 and spapr code
> ---
> hw/ppc/spapr.c | 8 ++++----
> hw/ppc/spapr_softmmu.c | 2 +-
> target/ppc/mmu-hash64.c | 4 ++--
> target/ppc/mmu-hash64.h | 5 +++++
> 4 files changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 163c90388a..8ebf85bad8 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1414,7 +1414,7 @@ void spapr_store_hpte(PowerPCCPU *cpu, hwaddr ptex,
> kvmppc_write_hpte(ptex, pte0, pte1);
> } else {
> if (pte0 & HPTE64_V_VALID) {
> - stq_p(spapr->htab + offset + HASH_PTE_SIZE_64 / 2, pte1);
> + stq_p(spapr->htab + offset + HPTE64_R_BYTE_OFFSET, pte1);
Urgh.. so, initially I thought this was wrong because I was confusing
HPTE64_R_BYTE_OFFSET with HPTE64_R_R_BYTE_OFFSET. I doubt I'd be the
only one.
Calling something a BYTE_OFFSET then doing an stq to it is pretty
misleading I think. WORD1_OFFSET or R_WORD_OFFSET might be better?
Or you could change these writebacks to byte writes, as powernv has
already been changed. I'm not sure if that's necessary in the case of
pseries - since in that case the HPT doesn't exist within the guest's
address space.
> /*
> * When setting valid, we write PTE1 first. This ensures
> * proper synchronization with the reading code in
> @@ -1430,7 +1430,7 @@ void spapr_store_hpte(PowerPCCPU *cpu, hwaddr ptex,
> * ppc_hash64_pteg_search()
> */
> smp_wmb();
> - stq_p(spapr->htab + offset + HASH_PTE_SIZE_64 / 2, pte1);
> + stq_p(spapr->htab + offset + HPTE64_R_BYTE_OFFSET, pte1);
> }
> }
> }
> @@ -1438,7 +1438,7 @@ void spapr_store_hpte(PowerPCCPU *cpu, hwaddr ptex,
> static void spapr_hpte_set_c(PPCVirtualHypervisor *vhyp, hwaddr ptex,
> uint64_t pte1)
> {
> - hwaddr offset = ptex * HASH_PTE_SIZE_64 + 15;
> + hwaddr offset = ptex * HASH_PTE_SIZE_64 + HPTE64_R_C_BYTE_OFFSET;
> SpaprMachineState *spapr = SPAPR_MACHINE(vhyp);
>
> if (!spapr->htab) {
> @@ -1454,7 +1454,7 @@ static void spapr_hpte_set_c(PPCVirtualHypervisor
> *vhyp, hwaddr ptex,
> static void spapr_hpte_set_r(PPCVirtualHypervisor *vhyp, hwaddr ptex,
> uint64_t pte1)
> {
> - hwaddr offset = ptex * HASH_PTE_SIZE_64 + 14;
> + hwaddr offset = ptex * HASH_PTE_SIZE_64 + HPTE64_R_R_BYTE_OFFSET;
> SpaprMachineState *spapr = SPAPR_MACHINE(vhyp);
>
> if (!spapr->htab) {
> diff --git a/hw/ppc/spapr_softmmu.c b/hw/ppc/spapr_softmmu.c
> index f8924270ef..03676c4448 100644
> --- a/hw/ppc/spapr_softmmu.c
> +++ b/hw/ppc/spapr_softmmu.c
> @@ -426,7 +426,7 @@ static void new_hpte_store(void *htab, uint64_t pteg, int
> slot,
> addr += slot * HASH_PTE_SIZE_64;
>
> stq_p(addr, pte0);
> - stq_p(addr + HASH_PTE_SIZE_64 / 2, pte1);
> + stq_p(addr + HPTE64_R_BYTE_OFFSET, pte1);
> }
>
> static int rehash_hpte(PowerPCCPU *cpu,
> diff --git a/target/ppc/mmu-hash64.c b/target/ppc/mmu-hash64.c
> index 19832c4b46..168d397c26 100644
> --- a/target/ppc/mmu-hash64.c
> +++ b/target/ppc/mmu-hash64.c
> @@ -786,7 +786,7 @@ static void ppc_hash64_set_dsi(CPUState *cs, int mmu_idx,
> uint64_t dar, uint64_t
>
> static void ppc_hash64_set_r(PowerPCCPU *cpu, hwaddr ptex, uint64_t pte1)
> {
> - hwaddr base, offset = ptex * HASH_PTE_SIZE_64 + 16;
> + hwaddr base, offset = ptex * HASH_PTE_SIZE_64 + HPTE64_R_R_BYTE_OFFSET;
>
> if (cpu->vhyp) {
> PPCVirtualHypervisorClass *vhc =
> @@ -803,7 +803,7 @@ static void ppc_hash64_set_r(PowerPCCPU *cpu, hwaddr
> ptex, uint64_t pte1)
>
> static void ppc_hash64_set_c(PowerPCCPU *cpu, hwaddr ptex, uint64_t pte1)
> {
> - hwaddr base, offset = ptex * HASH_PTE_SIZE_64 + 15;
> + hwaddr base, offset = ptex * HASH_PTE_SIZE_64 + HPTE64_R_C_BYTE_OFFSET;
>
> if (cpu->vhyp) {
> PPCVirtualHypervisorClass *vhc =
> diff --git a/target/ppc/mmu-hash64.h b/target/ppc/mmu-hash64.h
> index c5b2f97ff7..2a46763f70 100644
> --- a/target/ppc/mmu-hash64.h
> +++ b/target/ppc/mmu-hash64.h
> @@ -97,6 +97,11 @@ void ppc_hash64_finalize(PowerPCCPU *cpu);
> #define HPTE64_V_1TB_SEG 0x4000000000000000ULL
> #define HPTE64_V_VRMA_MASK 0x4001ffffff000000ULL
>
> +/* PTE byte offsets */
> +#define HPTE64_R_R_BYTE_OFFSET 14
> +#define HPTE64_R_C_BYTE_OFFSET 15
> +#define HPTE64_R_BYTE_OFFSET (HASH_PTE_SIZE_64 / 2)
> +
> /* Format changes for ARCH v3 */
> #define HPTE64_V_COMMON_BITS 0x000fffffffffffffULL
> #define HPTE64_R_3_0_SSIZE_SHIFT 58
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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