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Re: [Xen-devel] [RFC PATCH v2 1/8] arm/mem_access: Add (TCR_|TTBCR_)* defines





On 07/06/17 15:56, Sergej Proskurin wrote:
Hi Julien,

[...]



Also, a lot of the new defines you add are for TCR_EL1 and not TCR_EL2.
Please make the distinction in the name to avoid misusing them.

+
+#define TCR_TB_31       (31)
    #ifdef CONFIG_ARM_64
    #define TCR_PS(x)       ((x)<<16)
  #define TCR_TBI         (_AC(0x1,UL)<<20)
+#define TCR_TBI0        (_AC(0x1,UL)<<37)
+#define TCR_TBI1        (_AC(0x1,UL)<<38)

Those fields don't exist in TCR_EL2.

This is not entirely correct. All of the introduced fields are also
available in TCR_EL2, however, only if HCR_EL2.E2H==1. I will comment
that appropriately. Do you think that we should use nevertheless
different names for the introduced defines?


This was added by ARMv8.1. HCR_EL2.E2H = 1 as is to run Host Operating System in EL2 (e.g for Type-2 hypervisor). This will very never be used by Xen.

In any case, the naming gives the impression it also exists when HCR_EL2.E2H = 0.

Cheers,

--
Julien Grall

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