Mailing List Archive: Libxc code to get MTRR memory type for physical address pa

Libxc code to get MTRR memory type for physical address pa

Dec 13, 2012, 7:13 AM

Post #1 of 3 (195 views)

Hello,

what would be the libxc-based equivalent of get_mtrr_type(struct
mtrr_state *m, paddr_t pa) (from xen/arch/x86/hvm/mtrr.c)?

I've searched the source code and found this:

struct hvm_hw_mtrr {
#define MTRR_VCNT 8
#define NUM_FIXED_MSR 11
uint64_t msr_pat_cr;
/* mtrr physbase & physmask msr pair*/
uint64_t msr_mtrr_var[MTRR_VCNT*2];
uint64_t msr_mtrr_fixed[NUM_FIXED_MSR];
uint64_t msr_mtrr_cap;
uint64_t msr_mtrr_def_type;
};

in xen/include/public/arch-x86/hvm/save.h. I can retrieve that using
xc_domain_hvm_getcontext_partial(), but what would the the best way to
get the uint8_t result, for a given 'pa', that get_mtrr_type() returns?

Thanks,
Razvan Cojocaru

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Re: Libxc code to get MTRR memory type for physical address pa [ In reply to ]

tim at xen

Dec 13, 2012, 9:21 AM

Post #2 of 3 (188 views)

Permalink

At 17:13 +0200 on 13 Dec (1355418813), Razvan Cojocaru wrote:
> Hello,
>
> what would be the libxc-based equivalent of get_mtrr_type(struct
> mtrr_state *m, paddr_t pa) (from xen/arch/x86/hvm/mtrr.c)?
>
> I've searched the source code and found this:
>
> struct hvm_hw_mtrr {
> #define MTRR_VCNT 8
> #define NUM_FIXED_MSR 11
> uint64_t msr_pat_cr;
> /* mtrr physbase & physmask msr pair*/
> uint64_t msr_mtrr_var[MTRR_VCNT*2];
> uint64_t msr_mtrr_fixed[NUM_FIXED_MSR];
> uint64_t msr_mtrr_cap;
> uint64_t msr_mtrr_def_type;
> };
>
> in xen/include/public/arch-x86/hvm/save.h. I can retrieve that using
> xc_domain_hvm_getcontext_partial(), but what would the the best way to
> get the uint8_t result, for a given 'pa', that get_mtrr_type() returns?

I think you'd have to write some code to decode the MTRRs, by copying
the logic that Xen uses in get_mtrr_type (or by following the processor
manuals).

If you do, please send a patch to add it to libxc for the next person!

Tim.

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Re: Libxc code to get MTRR memory type for physical address pa [ In reply to ]

rzvncj at gmail

Dec 13, 2012, 9:32 AM

Post #3 of 3 (188 views)

Permalink

> I think you'd have to write some code to decode the MTRRs, by copying
> the logic that Xen uses in get_mtrr_type (or by following the processor
> manuals).
>
> If you do, please send a patch to add it to libxc for the next person!

Ah, I thought it might come to this. :) Of course, if I end up doing it
I'll happily contribute the patch.

Thanks,
Razvan Cojocaru

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