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Re: [Qemu-ppc] [PATCHv2] spapr: Correct RAM size calculation for HPT res
From: |
Greg Kurz |
Subject: |
Re: [Qemu-ppc] [PATCHv2] spapr: Correct RAM size calculation for HPT resizing |
Date: |
Wed, 11 Oct 2017 08:06:03 +0200 |
On Wed, 11 Oct 2017 11:06:49 +1100
David Gibson <address@hidden> wrote:
> In order to prevent the guest from forcing the allocation of large amounts
> of qemu memory (or host kernel memory, in the case of KVM HV), we limit
> the size of Hashed Page Table (HPT) it is allowed to allocated, based on
> its RAM size.
>
> However, the current calculation is not correct: it only adds up the size
> of plugged memory, ignoring the base memory size. This patch corrects it.
>
> While we're there, use get_plugged_memory_size() instead of directly
> calling pc_existing_dimms_capacity(). The only difference is that it
> will abort on failure, which is right: a failure here indicates something
> wrong within qemu.
>
> Signed-off-by: David Gibson <address@hidden>
> ---
> hw/ppc/spapr_hcall.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> Changes in v2:
> * Also remove redundant initializer of current_ram_size
>
* And use ram_size machine attribute instead of the ram_size global.
Reviewed-by: Greg Kurz <address@hidden>
> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> index 8d72bb7c1c..0d59d1534d 100644
> --- a/hw/ppc/spapr_hcall.c
> +++ b/hw/ppc/spapr_hcall.c
> @@ -472,7 +472,7 @@ static target_ulong h_resize_hpt_prepare(PowerPCCPU *cpu,
> target_ulong flags = args[0];
> int shift = args[1];
> sPAPRPendingHPT *pending = spapr->pending_hpt;
> - uint64_t current_ram_size = MACHINE(spapr)->ram_size;
> + uint64_t current_ram_size;
> int rc;
>
> if (spapr->resize_hpt == SPAPR_RESIZE_HPT_DISABLED) {
> @@ -494,7 +494,7 @@ static target_ulong h_resize_hpt_prepare(PowerPCCPU *cpu,
> return H_PARAMETER;
> }
>
> - current_ram_size = pc_existing_dimms_capacity(&error_fatal);
> + current_ram_size = MACHINE(spapr)->ram_size + get_plugged_memory_size();
>
> /* We only allow the guest to allocate an HPT one order above what
> * we'd normally give them (to stop a small guest claiming a huge