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xen/riscv: add VM space layout
Also it was added explanation about ignoring of top VA bits Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com> Acked-by: Bobby Eshleman <bobbyeshleman@gmail.com>
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Oleksii Kurochko authored and Jan Beulich committed
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+36
@@ -4,6 +4,42 @@
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#include <xen/const.h>
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#include <xen/page-size.h>
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/*
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* RISC-V64 Layout:
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*
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#if RV_STAGE1_MODE == SATP_MODE_SV39
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*
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* From the riscv-privileged doc:
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* When mapping between narrower and wider addresses,
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* RISC-V zero-extends a narrower physical address to a wider size.
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* The mapping between 64-bit virtual addresses and the 39-bit usable
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* address space of Sv39 is not based on zero-extension but instead
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* follows an entrenched convention that allows an OS to use one or
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* a few of the most-significant bits of a full-size (64-bit) virtual
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* address to quickly distinguish user and supervisor address regions.
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*
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* It means that:
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* top VA bits are simply ignored for the purpose of translating to PA.
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*
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* ============================================================================
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* Start addr | End addr | Size | Slot |area description
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* ============================================================================
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* FFFFFFFFC0800000 | FFFFFFFFFFFFFFFF |1016 MB | L2 511 | Unused
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* FFFFFFFFC0600000 | FFFFFFFFC0800000 | 2 MB | L2 511 | Fixmap
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* FFFFFFFFC0200000 | FFFFFFFFC0600000 | 4 MB | L2 511 | FDT
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* FFFFFFFFC0000000 | FFFFFFFFC0200000 | 2 MB | L2 511 | Xen
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* ... | 1 GB | L2 510 | Unused
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* 0000003200000000 | 0000007F80000000 | 309 GB | L2 200-509 | Direct map
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* ... | 1 GB | L2 199 | Unused
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* 0000003100000000 | 00000031C0000000 | 3 GB | L2 196-198 | Frametable
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* ... | 1 GB | L2 195 | Unused
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* 0000003080000000 | 00000030C0000000 | 1 GB | L2 194 | VMAP
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* ... | 194 GB | L2 0 - 193 | Unused
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* ============================================================================
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*
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#endif
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*/
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#if defined(CONFIG_RISCV_64)
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# define LONG_BYTEORDER 3
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# define ELFSIZE 64
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