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Re: [PATCH v5 3/3] spapr_numa: use spapr_numa_get_vcpu_assoc() in home_n
From: |
Greg Kurz |
Subject: |
Re: [PATCH v5 3/3] spapr_numa: use spapr_numa_get_vcpu_assoc() in home_node hcall |
Date: |
Fri, 4 Sep 2020 16:41:03 +0200 |
On Fri, 4 Sep 2020 10:56:31 -0300
Daniel Henrique Barboza <danielhb413@gmail.com> wrote:
> The current implementation of h_home_node_associativity hard codes
> the values of associativity domains of the vcpus. Let's make
> it consider the values already initialized in spapr->numa_assoc_array,
> via the spapr_numa_get_vcpu_assoc() helper.
>
> We want to set it and forget it, and for that we also need to
> assert that we don't overflow the registers of the hypercall.
> From R4 to R9 we can squeeze in 12 associativity domains for
> vcpus, so let's assert that VCPU_ASSOC_SIZE -1 isn't greater
> than that.
>
> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
> ---
> hw/ppc/spapr_numa.c | 41 +++++++++++++++++++++++++++++++++--------
> 1 file changed, 33 insertions(+), 8 deletions(-)
>
> diff --git a/hw/ppc/spapr_numa.c b/hw/ppc/spapr_numa.c
> index 674d2ee86d..07eb921737 100644
> --- a/hw/ppc/spapr_numa.c
> +++ b/hw/ppc/spapr_numa.c
> @@ -178,10 +178,11 @@ static target_ulong
> h_home_node_associativity(PowerPCCPU *cpu,
> target_ulong opcode,
> target_ulong *args)
> {
> + g_autofree uint32_t *vcpu_assoc = NULL;
> target_ulong flags = args[0];
> target_ulong procno = args[1];
> PowerPCCPU *tcpu;
> - int idx;
> + int idx, assoc_idx;
>
> /* only support procno from H_REGISTER_VPA */
> if (flags != 0x1) {
> @@ -193,16 +194,40 @@ static target_ulong
> h_home_node_associativity(PowerPCCPU *cpu,
> return H_P2;
> }
>
> - /* sequence is the same as in the "ibm,associativity" property */
> + /*
> + * Given that we want to be flexible with the sizes and indexes,
> + * we must consider that there is a hard limit of how many
> + * associativities domain we can fit in R4 up to R9, which would be
> + * 12 associativity domains for vcpus. Assert and bail if that's
> + * not the case.
> + */
> + G_STATIC_ASSERT((VCPU_ASSOC_SIZE - 1) <= 12);
> +
> + vcpu_assoc = spapr_numa_get_vcpu_assoc(spapr, tcpu);
> + /* assoc_idx starts at 1 to skip associativity size */
> + assoc_idx = 1;
>
> - idx = 0;
> #define ASSOCIATIVITY(a, b) (((uint64_t)(a) << 32) | \
> ((uint64_t)(b) & 0xffffffff))
> - args[idx++] = ASSOCIATIVITY(0, 0);
> - args[idx++] = ASSOCIATIVITY(0, tcpu->node_id);
> - args[idx++] = ASSOCIATIVITY(procno, -1);
> - for ( ; idx < 6; idx++) {
> - args[idx] = -1;
> +
> + for (idx = 0; idx < 6; idx++) {
> + int32_t a, b;
> +
> + /*
> + * vcpu_assoc[] will contain the associativity domains for tcpu,
> + * including tcpu->node_id and procno, meaning that we don't
> + * need to use these variables here.
> + *
> + * We'll read 2 values at a time to fill up the ASSOCIATIVITY()
> + * macro. The ternary will fill the remaining registers with -1
> + * after we went through vcpu_assoc[].
> + */
> + a = assoc_idx < VCPU_ASSOC_SIZE ?
> + be32_to_cpu(vcpu_assoc[assoc_idx++]) : -1;
> + b = assoc_idx < VCPU_ASSOC_SIZE ?
> + be32_to_cpu(vcpu_assoc[assoc_idx++]) : -1;
> +
> + args[idx] = ASSOCIATIVITY(a, b);
> }
> #undef ASSOCIATIVITY
>
Much clearer with the comment.
Reviewed-by: Greg Kurz <groug@kaod.org>