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Re: [PATCH v1 03/15] xen/riscv: implement vcpu_csr_init()
- To: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Mon, 12 Jan 2026 15:28:43 +0100
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- Cc: Alistair Francis <alistair.francis@xxxxxxx>, Bob Eshleman <bobbyeshleman@xxxxxxxxx>, Connor Davis <connojdavis@xxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Julien Grall <julien@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Mon, 12 Jan 2026 14:28:53 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 12.01.2026 13:59, Oleksii Kurochko wrote:
> On 1/7/26 9:46 AM, Jan Beulich wrote:
>> Also, wouldn't you better keep internal state in line with what hardware
>> actually supports? CSRIND may be read-only-zero in the real register, in
>> which case having the bit set in the "cached" copy can be misleading.
>
> [...]
>
>> (This may similarly apply to at least hedeleg and hideleg, btw.)
>
> Regarding the previous bits, I can understand that it would be an issue:
> if SSAIA isn’t supported, then it is incorrect to update the corresponding
> bits of|hstateen0|.
>
> However, I’m not really sure I understand what the issue is with|h{i,e}deleg|.
> All writable bits there don’t depend on hardware support. Am I missing
> something?
My reading of the doc was that any of the bits can be r/o 0, with - yes -
no dependencies on particular extensions. In which case you'd need to do
the delegation in software. For which it might be helpful to know what
the two registers are actually set to in hardware (i.e. the cached values
wanting to match the real ones).
Jan
|
