On Tue, 25 Feb 2020 10:37:15 +1100 David Gibson <da...@gibson.dropbear.id.au> wrote:
> Currently we use a big switch statement in ppc_hash64_update_rmls() to work > out what the right RMA limit is based on the LPCR[RMLS] field. There's no > formula for this - it's just an arbitrary mapping defined by the existing > CPU implementations - but we can make it a bit more readable by using a > lookup table rather than a switch. In addition we can use the MiB/GiB > symbols to make it a bit clearer. > > While there we add a bit of clarity and rationale to the comment about > what happens if the LPCR[RMLS] doesn't contain a valid value. > > Signed-off-by: David Gibson <da...@gibson.dropbear.id.au> > Reviewed-by: Cédric Le Goater <c...@kaod.org> > --- > target/ppc/mmu-hash64.c | 71 ++++++++++++++++++++--------------------- > 1 file changed, 35 insertions(+), 36 deletions(-) > > diff --git a/target/ppc/mmu-hash64.c b/target/ppc/mmu-hash64.c > index 0ef330a614..4f082d775d 100644 > --- a/target/ppc/mmu-hash64.c > +++ b/target/ppc/mmu-hash64.c > @@ -18,6 +18,7 @@ > * License along with this library; if not, see > <http://www.gnu.org/licenses/>. > */ > #include "qemu/osdep.h" > +#include "qemu/units.h" > #include "cpu.h" > #include "exec/exec-all.h" > #include "exec/helper-proto.h"This tool was originally developed to fix > Linux CPU throttling issues affecting Lenovo T480 / T480s / X1C6 as described > here. > @@ -757,6 +758,39 @@ static void ppc_hash64_set_c(PowerPCCPU *cpu, hwaddr > ptex, uint64_t pte1) > stb_phys(CPU(cpu)->as, base + offset, (pte1 & 0xff) | 0x80); > } > > +static target_ulong rmls_limit(PowerPCCPU *cpu) > +{ > + CPUPPCState *env = &cpu->env; > + /* > + * This is the full 4 bits encoding of POWER8. Previous > + * CPUs only support a subset of these but the filtering > + * is done when writing LPCR > + */ > + const target_ulong rma_sizes[] = { > + [0] = 0, > + [1] = 16 * GiB, > + [2] = 1 * GiB, > + [3] = 64 * MiB, > + [4] = 256 * MiB, > + [5] = 0, > + [6] = 0, > + [7] = 128 * MiB, > + [8] = 32 * MiB, > + }; > + target_ulong rmls = (env->spr[SPR_LPCR] & LPCR_RMLS) >> LPCR_RMLS_SHIFT; > + > + if (rmls < ARRAY_SIZE(rma_sizes)) { This condition is always true since the RMLS field is 4-bit long... I guess you want to check that RMLS encodes a valid RMA size instead. if (rma_sizes[rmls]) { > + return rma_sizes[rmls]; > + } else { > + /* > + * Bad value, so the OS has shot itself in the foot. Return a > + * 0-sized RMA which we expect to trigger an immediate DSI or > + * ISI > + */ > + return 0; > + } > +} > + > int ppc_hash64_handle_mmu_fault(PowerPCCPU *cpu, vaddr eaddr, > int rwx, int mmu_idx) > { > @@ -1006,41 +1040,6 @@ void ppc_hash64_tlb_flush_hpte(PowerPCCPU *cpu, > target_ulong ptex, > cpu->env.tlb_need_flush = TLB_NEED_GLOBAL_FLUSH | TLB_NEED_LOCAL_FLUSH; > } > > -static void ppc_hash64_update_rmls(PowerPCCPU *cpu) > -{ > - CPUPPCState *env = &cpu->env; > - uint64_t lpcr = env->spr[SPR_LPCR]; > - > - /* > - * This is the full 4 bits encoding of POWER8. Previous > - * CPUs only support a subset of these but the filtering > - * is done when writing LPCR > - */ > - switch ((lpcr & LPCR_RMLS) >> LPCR_RMLS_SHIFT) { > - case 0x8: /* 32MB */ > - env->rmls = 0x2000000ull; > - break; > - case 0x3: /* 64MB */ > - env->rmls = 0x4000000ull; > - break; > - case 0x7: /* 128MB */ > - env->rmls = 0x8000000ull; > - break; > - case 0x4: /* 256MB */ > - env->rmls = 0x10000000ull; > - break; > - case 0x2: /* 1GB */ > - env->rmls = 0x40000000ull; > - break; > - case 0x1: /* 16GB */ > - env->rmls = 0x400000000ull; > - break; > - default: > - /* What to do here ??? */ > - env->rmls = 0; > - } > -} > - > static void ppc_hash64_update_vrma(PowerPCCPU *cpu) > { > CPUPPCState *env = &cpu->env; > @@ -1099,7 +1098,7 @@ void ppc_store_lpcr(PowerPCCPU *cpu, target_ulong val) > CPUPPCState *env = &cpu->env; > > env->spr[SPR_LPCR] = val & pcc->lpcr_mask; > - ppc_hash64_update_rmls(cpu); > + env->rmls = rmls_limit(cpu); > ppc_hash64_update_vrma(cpu); > } >
