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| author | David Gibson <david@gibson.dropbear.id.au> | 2017-07-12 17:56:06 +1000 |
|---|---|---|
| committer | David Gibson <david@gibson.dropbear.id.au> | 2017-07-17 15:07:05 +1000 |
| commit | 2772cf6be90e39919d0557ba3c57a77313ca9edf (patch) | |
| tree | 5e763df3359b48a82e0cf45aef17d2fd57401441 /include | |
| parent | 52b81ab5e95a64cb6973fc4d60d2319c4305ddf8 (diff) | |
| download | qemu-2772cf6be90e39919d0557ba3c57a77313ca9edf.zip qemu-2772cf6be90e39919d0557ba3c57a77313ca9edf.tar.gz qemu-2772cf6be90e39919d0557ba3c57a77313ca9edf.tar.bz2 | |
pseries: Use smaller default hash page tables when guest can resize
We've now implemented a PAPR extension allowing PAPR guest to resize
their hash page table (HPT) during runtime.
This patch makes use of that facility to allocate smaller HPTs by default.
Specifically when a guest is aware of the HPT resize facility, qemu sizes
the HPT to the initial memory size, rather than the maximum memory size on
the assumption that the guest will resize its HPT if necessary for hot
plugged memory.
When the initial memory size is much smaller than the maximum memory size
(a common configuration with e.g. oVirt / RHEV) then this can save
significant memory on the HPT.
If the guest does *not* advertise HPT resize awareness when it makes the
ibm,client-architecture-support call, qemu resizes the HPT for maxmimum
memory size (unless it's been configured not to allow such guests at all).
For now we make that reallocation assuming the guest has not yet used the
HPT at all. That's true in practice, but not, strictly, an architectural
or PAPR requirement. If we need to in future we can fix this by having
the client-architecture-support call reboot the guest with the revised
HPT size (the client-architecture-support call is explicitly permitted to
trigger a reboot in this way).
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/hw/ppc/spapr.h | 2 | ||||
| -rw-r--r-- | include/hw/ppc/spapr_ovec.h | 1 |
2 files changed, 3 insertions, 0 deletions
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h index 3dd62d8..2a303a7 100644 --- a/include/hw/ppc/spapr.h +++ b/include/hw/ppc/spapr.h @@ -660,6 +660,8 @@ void spapr_hotplug_req_remove_by_count_indexed(sPAPRDRConnectorType drc_type, uint32_t count, uint32_t index); void spapr_cpu_parse_features(sPAPRMachineState *spapr); int spapr_hpt_shift_for_ramsize(uint64_t ramsize); +void spapr_reallocate_hpt(sPAPRMachineState *spapr, int shift, + Error **errp); /* CPU and LMB DRC release callbacks. */ void spapr_core_release(DeviceState *dev); diff --git a/include/hw/ppc/spapr_ovec.h b/include/hw/ppc/spapr_ovec.h index 0b464e2..9edfa5f 100644 --- a/include/hw/ppc/spapr_ovec.h +++ b/include/hw/ppc/spapr_ovec.h @@ -50,6 +50,7 @@ typedef struct sPAPROptionVector sPAPROptionVector; #define OV5_DRCONF_MEMORY OV_BIT(2, 2) #define OV5_FORM1_AFFINITY OV_BIT(5, 0) #define OV5_HP_EVT OV_BIT(6, 5) +#define OV5_HPT_RESIZE OV_BIT(6, 7) #define OV5_XIVE_EXPLOIT OV_BIT(23, 7) /* ISA 3.00 MMU features: */ |