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Re: [Qemu-devel] i386: pc: align gpa<->hpa on 1GB boundary (v3)
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] i386: pc: align gpa<->hpa on 1GB boundary (v3) |
Date: |
Wed, 06 Nov 2013 13:07:26 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130923 Thunderbird/17.0.9 |
Il 06/11/2013 12:59, Igor Mammedov ha scritto:
> On Tue, 5 Nov 2013 23:55:43 -0200
> Marcelo Tosatti <address@hidden> wrote:
>
>>
>>
>> v2: condition enablement of new mapping to new machine types (Paolo)
>> v3: fix changelog
>>
>> -----
>>
>>
>> Align guest physical address and host physical address
>> beyond guest 4GB on a 1GB boundary.
>>
>> Otherwise 1GB TLBs cannot be cached for the range.
>>
>> Signed-off-by: Marcelo Tosatti <address@hidden>
>>
>> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
>> index 0c313fe..534e067 100644
>> --- a/hw/i386/pc.c
>> +++ b/hw/i386/pc.c
>> @@ -1116,7 +1116,7 @@ FWCfgState *pc_memory_init(MemoryRegion *system_memory,
> [...]
>> + /*
>> + *
>> + * If 1GB hugepages are used to back guest RAM, map guest address
>> + * space in the range [ramsize,ramsize+holesize] to the ram block
>> + * range [holestart, 4GB]
>> + *
>> + * 0 h 4G
>> [ramsize,ramsize+holesize]
>> + *
>> + * guest-addr-space [ ] [ ][xxx]
>> + * /----------/
>> + * contiguous-ram-block [ ][xxx][ ]
>> + *
>> + * So that memory beyond 4GB is aligned on a 1GB boundary,
>> + * at the host physical address space.
>> + *
>> + */
>> + if (guest_info->gb_align) {
> 'gb_align' is one shot usage, it would be better to just add it as an argument
> to pc_memory_init(). That would allow to avoid extending PcGuestInfo
> needlessly,
> since gb_align isn't reused.
No, Marcelo's way is better. pc_memory_init already has too many
arguments, moving them to PcGuestInfo (which ultimately might become
properties of the /machine QOM object) is the right thing to do.
Paolo
>> + unsigned long holesize = 0x100000000ULL - below_4g_mem_size;
>> +
>> + memory_region_init_alias(ram_above_4g, NULL, "ram-above-4g",
>> ram,
>> + 0x100000000ULL,
>> + above_4g_mem_size - holesize);
>> + memory_region_add_subregion(system_memory, 0x100000000ULL,
>> ram_above_4g);
> [...]
>> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
>> index 6083839..00afe4a 100644
>> --- a/include/hw/i386/pc.h
>> +++ b/include/hw/i386/pc.h
>> @@ -20,6 +20,7 @@ typedef struct PcPciInfo {
>> struct PcGuestInfo {
>> bool has_pci_info;
>> bool isapc_ram_fw;
>> + bool gb_align;
>> FWCfgState *fw_cfg;
>> };
> it doesn't apply anymore.
>
- [Qemu-devel] i386: pc: align gpa<->hpa on 1GB boundary (v2), Marcelo Tosatti, 2013/11/05
- [Qemu-devel] i386: pc: align gpa<->hpa on 1GB boundary (v4), Marcelo Tosatti, 2013/11/06
- Re: [Qemu-devel] i386: pc: align gpa<->hpa on 1GB boundary (v4), Igor Mammedov, 2013/11/07
- Re: [Qemu-devel] i386: pc: align gpa<->hpa on 1GB boundary (v4), Marcelo Tosatti, 2013/11/07
- [Qemu-devel] i386: pc: align gpa<->hpa on 1GB boundary (v5), Marcelo Tosatti, 2013/11/10