Commit e957f6a9 authored by Sam Bobroff's avatar Sam Bobroff Committed by David Gibson
Browse files

spapr: Workaround for broken radix guests 



For a little while around 4.9, Linux kernels that saw the radix bit in
ibm,pa-features would attempt to set up the MMU as if they were a
hypervisor, even if they were a guest, which would cause them to
crash.

Work around this by detecting pre-ISA 3.0 guests by their lack of that
bit in option vector 1, and then removing the radix bit from
ibm,pa-features. Note: This now requires regeneration of that node
after CAS negotiation.

Signed-off-by: default avatarSam Bobroff <sam.bobroff@au1.ibm.com>
[dwg: Fix style nits]
Signed-off-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
parent 9fb4541f

hw/ppc/spapr.c

+13 −2
Original line number Diff line number Diff line
@@ -228,7 +228,8 @@ static int spapr_fixup_cpu_numa_dt(void *fdt, int offset, CPUState *cs) 
}



/* Populate the "ibm,pa-features" property */

static void spapr_populate_pa_features(CPUPPCState *env, void *fdt, int offset)

static void spapr_populate_pa_features(CPUPPCState *env, void *fdt, int offset,

                                      bool legacy_guest)

{

    uint8_t pa_features_206[] = { 6, 0,

        0xf6, 0x1f, 0xc7, 0x00, 0x80, 0xc0 };
@@ -295,6 +296,12 @@ static void spapr_populate_pa_features(CPUPPCState *env, void *fdt, int offset) 
    if (kvmppc_has_cap_htm() && pa_size > 24) {

        pa_features[24] |= 0x80;    /* Transactional memory support */

    }

    if (legacy_guest && pa_size > 40) {

        /* Workaround for broken kernels that attempt (guest) radix

         * mode when they can't handle it, if they see the radix bit set

         * in pa-features. So hide it from them. */

        pa_features[40 + 2] &= ~0x80; /* Radix MMU */

    }



    _FDT((fdt_setprop(fdt, offset, "ibm,pa-features", pa_features, pa_size)));

}
@@ -309,6 +316,7 @@ static int spapr_fixup_cpu_dt(void *fdt, sPAPRMachineState *spapr) 


    CPU_FOREACH(cs) {

        PowerPCCPU *cpu = POWERPC_CPU(cs);

        CPUPPCState *env = &cpu->env;

        DeviceClass *dc = DEVICE_GET_CLASS(cs);

        int index = ppc_get_vcpu_dt_id(cpu);

        int compat_smt = MIN(smp_threads, ppc_compat_max_threads(cpu));
@@ -350,6 +358,9 @@ static int spapr_fixup_cpu_dt(void *fdt, sPAPRMachineState *spapr) 
        if (ret < 0) {

            return ret;

        }



        spapr_populate_pa_features(env, fdt, offset,

                                         spapr->cas_legacy_guest_workaround);

    }

    return ret;

}
@@ -547,7 +558,7 @@ static void spapr_populate_cpu_dt(CPUState *cs, void *fdt, int offset, 
                          page_sizes_prop, page_sizes_prop_size)));

    }



    spapr_populate_pa_features(env, fdt, offset);

    spapr_populate_pa_features(env, fdt, offset, false);



    _FDT((fdt_setprop_cell(fdt, offset, "ibm,chip-id",

                           cs->cpu_index / vcpus_per_socket)));

hw/ppc/spapr_hcall.c

+4 −2
Original line number Diff line number Diff line
@@ -1062,7 +1062,7 @@ static target_ulong h_client_architecture_support(PowerPCCPU *cpu, 
    uint32_t max_compat = cpu->max_compat;

    uint32_t best_compat = 0;

    int i;

    sPAPROptionVector *ov5_guest, *ov5_cas_old, *ov5_updates;

    sPAPROptionVector *ov1_guest, *ov5_guest, *ov5_cas_old, *ov5_updates;

    bool guest_radix;



    /*
@@ -1114,6 +1114,7 @@ static target_ulong h_client_architecture_support(PowerPCCPU *cpu, 
    /* For the future use: here @ov_table points to the first option vector */

    ov_table = list;



    ov1_guest = spapr_ovec_parse_vector(ov_table, 1);

    ov5_guest = spapr_ovec_parse_vector(ov_table, 5);

    if (spapr_ovec_test(ov5_guest, OV5_MMU_BOTH)) {

        error_report("guest requested hash and radix MMU, which is invalid.");
@@ -1155,7 +1156,8 @@ static target_ulong h_client_architecture_support(PowerPCCPU *cpu, 
            exit(EXIT_FAILURE);

        }

    }



    spapr->cas_legacy_guest_workaround = !spapr_ovec_test(ov1_guest,

                                                          OV1_PPC_3_00);

    if (!spapr->cas_reboot) {

        spapr->cas_reboot =

            (spapr_h_cas_compose_response(spapr, args[1], args[2],

include/hw/ppc/spapr.h

+1 −0
Original line number Diff line number Diff line
@@ -89,6 +89,7 @@ struct sPAPRMachineState { 
    sPAPROptionVector *ov5;         /* QEMU-supported option vectors */

    sPAPROptionVector *ov5_cas;     /* negotiated (via CAS) option vectors */

    bool cas_reboot;

    bool cas_legacy_guest_workaround;



    Notifier epow_notifier;

    QTAILQ_HEAD(, sPAPREventLogEntry) pending_events;

include/hw/ppc/spapr_ovec.h

+3 −0
Original line number Diff line number Diff line
@@ -43,6 +43,9 @@ typedef struct sPAPROptionVector sPAPROptionVector; 


#define OV_BIT(byte, bit) ((byte - 1) * BITS_PER_BYTE + bit)



/* option vector 1 */

#define OV1_PPC_3_00            OV_BIT(3, 0) /* guest supports PowerPC 3.00? */



/* option vector 5 */

#define OV5_DRCONF_MEMORY       OV_BIT(2, 2)

#define OV5_FORM1_AFFINITY      OV_BIT(5, 0)