From: Richard Henderson <richard.henderson@linaro.org>
To: "Alex Bennée" <alex.bennee@linaro.org>, qemu-devel@nongnu.org
Cc: peter.maydell@linaro.org, beata.michalska@linaro.org
Subject: Re: [Qemu-devel] [PATCH for-4.2 12/24] target/arm: Add VHE system register redirection and aliasing
Date: Thu, 25 Jul 2019 07:24:11 -0700 [thread overview]
Message-ID: <6f561cff-b612-ae50-020f-7c66bac0f742@linaro.org> (raw)
In-Reply-To: <871rye1ad5.fsf@linaro.org>
On 7/25/19 7:01 AM, Alex Bennée wrote:
>> + union {
>> + /*
>> + * Offsets of the secure and non-secure fields in CPUARMState for
>> + * the register if it is banked. These fields are only used during
>> + * the static registration of a register. During hashing the bank
>> + * associated with a given security state is copied to fieldoffset
>> + * which is used from there on out.
>> + *
>> + * It is expected that register definitions use either fieldoffset
>> + * or bank_fieldoffsets in the definition but not both. It is also
>> + * expected that both bank offsets are set when defining a banked
>> + * register. This use indicates that a register is banked.
>> + */
>> + ptrdiff_t bank_fieldoffsets[2];
>
> It seems a bit off that we are compressing this structure into a union
> when we didn't bother with the above fieldoffset despite the statement
> that only one or the other is used.
...
> Is 2 pointers enough saving? Will we never see a re-directed register
> that was using the banked fieldoffsets? Can we protect against that?
It's because bank_fieldoffsets[] is only used before instantiation.
Before the structure is given to add_cpreg_to_hashtable, we have copied the
structure, copied bank_fieldoffsets into fieldoffset, and adjusted the secure
state flag.
After instantiation, those two pointers are unused, and I thought I could
reclaim it. However, you may have a point re total memory savings not making
the complication worthwhile.
r~
next prev parent reply other threads:[~2019-07-25 14:24 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-19 21:03 [Qemu-devel] [PATCH for-4.2 00/24] target/arm: Implement ARMv8.1-VHE Richard Henderson
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 01/24] cputlb: Add tlb_set_asid_for_mmuidx Richard Henderson
2019-07-22 9:53 ` Alex Bennée
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 02/24] cputlb: Add tlb_flush_asid_by_mmuidx and friends Richard Henderson
2019-07-22 10:04 ` Alex Bennée
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 03/24] target/arm: Install ASIDs for long-form from EL1 Richard Henderson
2019-07-22 15:28 ` Alex Bennée
2019-07-22 15:48 ` Richard Henderson
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 04/24] target/arm: Install ASIDs for short-form " Richard Henderson
2019-07-24 11:47 ` Alex Bennée
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 05/24] target/arm: Install ASIDs for EL2 Richard Henderson
2019-07-24 11:49 ` Alex Bennée
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 06/24] target/arm: Define isar_feature_aa64_vh Richard Henderson
2019-07-24 12:59 ` Alex Bennée
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 07/24] target/arm: Enable HCR_E2H for VHE Richard Henderson
2019-07-24 13:01 ` Alex Bennée
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 08/24] target/arm: Add CONTEXTIDR_EL2 Richard Henderson
2019-07-24 13:57 ` Alex Bennée
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 09/24] target/arm: Add TTBR1_EL2 Richard Henderson
2019-07-24 14:12 ` Alex Bennée
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 10/24] target/arm: Update CNTVCT_EL0 for VHE Richard Henderson
2019-07-24 14:47 ` Alex Bennée
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 11/24] target/arm: Add the hypervisor virtual counter Richard Henderson
2019-07-24 20:05 ` Alex Bennée
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 12/24] target/arm: Add VHE system register redirection and aliasing Richard Henderson
2019-07-25 14:01 ` Alex Bennée
2019-07-25 14:24 ` Richard Henderson [this message]
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 13/24] target/arm: Split out vae1_tlbmask, vmalle1_tlbmask Richard Henderson
2019-07-25 14:02 ` Alex Bennée
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 14/24] target/arm: Simplify tlb_force_broadcast alternatives Richard Henderson
2019-07-25 14:08 ` Alex Bennée
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 15/24] target/arm: Reorganize ARMMMUIdx Richard Henderson
2019-07-25 15:57 ` Alex Bennée
2019-07-25 18:18 ` Richard Henderson
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 16/24] target/arm: Add regime_has_2_ranges Richard Henderson
2019-07-25 15:59 ` Alex Bennée
2019-07-25 18:28 ` Richard Henderson
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 17/24] target/arm: Update arm_mmu_idx for VHE Richard Henderson
2019-07-25 16:01 ` Alex Bennée
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 18/24] target/arm: Update arm_sctlr " Richard Henderson
2019-07-25 16:02 ` Alex Bennée
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 19/24] target/arm: Install asids for E2&0 translation regime Richard Henderson
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 20/24] target/arm: Flush tlbs " Richard Henderson
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 21/24] target/arm: Update arm_phys_excp_target_el for TGE Richard Henderson
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 22/24] target/arm: Update regime_is_user for EL2&0 Richard Henderson
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 23/24] target/arm: Update {fp, sve}_exception_el for VHE Richard Henderson
2019-07-19 21:03 ` [Qemu-devel] [PATCH for-4.2 24/24] target/arm: Enable ARMv8.1-VHE in -cpu max Richard Henderson
2019-07-22 7:31 ` [Qemu-devel] [PATCH for-4.2 00/24] target/arm: Implement ARMv8.1-VHE Alex Bennée
2019-07-22 9:37 ` Alex Bennée
2019-07-22 15:10 ` Richard Henderson
2019-07-25 16:15 ` Alex Bennée
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