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Re: [PATCH v7 17/17] spapr: Fold spapr_node0_size() into its only caller
From: |
Greg Kurz |
Subject: |
Re: [PATCH v7 17/17] spapr: Fold spapr_node0_size() into its only caller |
Date: |
Tue, 3 Mar 2020 11:32:49 +0100 |
On Tue, 3 Mar 2020 14:43:51 +1100
David Gibson <address@hidden> wrote:
> The Real Mode Area (RMA) needs to fit within the NUMA node owning memory
> at address 0. That's usually node 0, but can be a later one if there are
> some nodes which have no memory (only CPUs).
>
> This is currently handled by the spapr_node0_size() helper. It has only
> one caller, so there's not a lot of point splitting it out. It's also
> extremely easy to misread the code as clamping to the size of the smallest
> node rather than the first node with any memory.
>
> So, fold it into the caller, and add some commentary to make it a bit
> clearer exactly what it's doing.
>
> Signed-off-by: David Gibson <address@hidden>
> ---
> hw/ppc/spapr.c | 37 +++++++++++++++++++++----------------
> 1 file changed, 21 insertions(+), 16 deletions(-)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 2eb0d8f70d..d674a9f48f 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -296,20 +296,6 @@ static void spapr_populate_pa_features(SpaprMachineState
> *spapr,
> _FDT((fdt_setprop(fdt, offset, "ibm,pa-features", pa_features,
> pa_size)));
> }
>
> -static hwaddr spapr_node0_size(MachineState *machine)
> -{
> - if (machine->numa_state->num_nodes) {
> - int i;
> - for (i = 0; i < machine->numa_state->num_nodes; ++i) {
> - if (machine->numa_state->nodes[i].node_mem) {
> - return MIN(pow2floor(machine->numa_state->nodes[i].node_mem),
> - machine->ram_size);
> - }
> - }
> - }
> - return machine->ram_size;
> -}
> -
> static void add_str(GString *s, const gchar *s1)
> {
> g_string_append_len(s, s1, strlen(s1) + 1);
> @@ -2653,10 +2639,24 @@ static hwaddr spapr_rma_size(SpaprMachineState
> *spapr, Error **errp)
> MachineState *machine = MACHINE(spapr);
> SpaprMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
> hwaddr rma_size = machine->ram_size;
> - hwaddr node0_size = spapr_node0_size(machine);
>
> /* RMA has to fit in the first NUMA node */
> - rma_size = MIN(rma_size, node0_size);
> + if (machine->numa_state->num_nodes) {
> + /*
> + * It's possible for there to be some zero-memory nodes first
> + * in the list. We need the RMA to fit inside the memory of
> + * the first node which actually has some memory.
> + */
> + int i;
> +
> + for (i = 0; i < machine->numa_state->num_nodes; ++i) {
> + if (machine->numa_state->nodes[i].node_mem != 0) {
> + rma_size = MIN(rma_size,
> + machine->numa_state->nodes[i].node_mem);
> + break;
> + }
> + }
> + }
>
> /*
> * VRMA access is via a special 1TiB SLB mapping, so the RMA can
> @@ -2673,6 +2673,11 @@ static hwaddr spapr_rma_size(SpaprMachineState *spapr,
> Error **errp)
> rma_size = MIN(rma_size, smc->rma_limit);
> }
>
> + /*
> + * RMA size must be a power of 2
> + */
> + rma_size = pow2floor(rma_size);
> +
I saw somewhere else that the reason behind this might be
related to:
https://git.qemu.org/?p=qemu.git;a=commitdiff;h=6010818c30ce9c
commit 6010818c30ce9c796b4e22fd261fc6fea1cecbfc
Author: Alexey Kardashevskiy <address@hidden>
Date: Thu Jul 3 13:10:05 2014 +1000
spapr: Split memory nodes to power-of-two blocks
Is this the reason ?
In any case, it would probably help to mention somewhere
why the rounding is introduced by this patch.
> if (rma_size < MIN_RMA_SLOF) {
> error_setg(errp,
> "pSeries SLOF firmware requires >= %ldMiB guest RMA (Real Mode Area memory)",
- Re: [PATCH v7 14/17] spapr: Don't attempt to clamp RMA to VRMA constraint, (continued)
- [PATCH v7 12/17] spapr: Don't use weird units for MIN_RMA_SLOF, David Gibson, 2020/03/02
- [PATCH v7 08/17] target/ppc: Streamline calculation of RMA limit from LPCR[RMLS], David Gibson, 2020/03/02
- [PATCH v7 10/17] target/ppc: Only calculate RMLS derived RMA limit on demand, David Gibson, 2020/03/02
- [PATCH v7 17/17] spapr: Fold spapr_node0_size() into its only caller, David Gibson, 2020/03/02
- Re: [PATCH v7 17/17] spapr: Fold spapr_node0_size() into its only caller,
Greg Kurz <=
- [PATCH v7 07/17] target/ppc: Use class fields to simplify LPCR masking, David Gibson, 2020/03/02
- [PATCH v7 09/17] target/ppc: Correct RMLS table, David Gibson, 2020/03/02
- [PATCH v7 15/17] spapr: Don't clamp RMA to 16GiB on new machine types, David Gibson, 2020/03/02
- [PATCH v7 13/17] spapr,ppc: Simplify signature of kvmppc_rma_size(), David Gibson, 2020/03/02