Re: [Qemu-ppc] [PATCH 1/6] target/ppc: Don't check UPRT in radix mode when in HV real mode

[David Gibson]

On Thu, Apr 11, 2019 at 09:59:59AM +0200, Cédric Le Goater wrote:
> From: Benjamin Herrenschmidt <address@hidden>
> 
> It appears that during kexec, we run for a while in hypervisor
> real mode with LPCR:HR set and LPCR:UPRT clear, which trips
> the assertion in ppc_radix64_handle_mmu_fault().
> 
> First this shouldn't be an assertion, it's a guest error.
> 
> Then we shouldn't be checking these things in hypervisor real
> mode (or in virtual hypervisor guest real mode which is similar)
> as the real HW won't use those LPCR bits in those cases anyway,
> so technically it's ok to have this discrepancy.
> 
> Signed-off-by: Benjamin Herrenschmidt <address@hidden>
> Signed-off-by: Cédric Le Goater <address@hidden>

Applied to ppc-for-4.1, thanks.

> ---
>  target/ppc/mmu-radix64.c | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/target/ppc/mmu-radix64.c b/target/ppc/mmu-radix64.c
> index ca1fb2673f93..cac076ee92d9 100644
> --- a/target/ppc/mmu-radix64.c
> +++ b/target/ppc/mmu-radix64.c
> @@ -228,10 +228,10 @@ int ppc_radix64_handle_mmu_fault(PowerPCCPU *cpu, vaddr 
> eaddr, int rwx,
>      ppc_v3_pate_t pate;
>  
>      assert((rwx == 0) || (rwx == 1) || (rwx == 2));
> -    assert(ppc64_use_proc_tbl(cpu));
>  
> -    /* Real Mode Access */
> -    if (((rwx == 2) && (msr_ir == 0)) || ((rwx != 2) && (msr_dr == 0))) {
> +    /* HV or virtual hypervisor Real Mode Access */
> +    if ((msr_hv || cpu->vhyp) &&
> +        (((rwx == 2) && (msr_ir == 0)) || ((rwx != 2) && (msr_dr == 0)))) {

Hrm.. this looks like a different bug fix.  Were we preivously
incorrectly handling guest real mode when running powernv?

>          /* In real mode top 4 effective addr bits (mostly) ignored */
>          raddr = eaddr & 0x0FFFFFFFFFFFFFFFULL;
>  
> @@ -241,6 +241,16 @@ int ppc_radix64_handle_mmu_fault(PowerPCCPU *cpu, vaddr 
> eaddr, int rwx,
>          return 0;
>      }
>  
> +    /*
> +     * Check UPRT (we avoid the check in real mode to deal with
> +     * transitional states during kexec.
> +     */
> +    if (!ppc64_use_proc_tbl(cpu)) {
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "LPCR:UPRT not set in radix mode ! LPCR=%016lx\n",
> +                      env->spr[SPR_LPCR]);
> +    }
> +
>      /* Virtual Mode Access - get the fully qualified address */
>      if (!ppc_radix64_get_fully_qualified_addr(env, eaddr, &lpid, &pid)) {
>          ppc_radix64_raise_segi(cpu, rwx, eaddr);

-- 
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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