From: Michal Orzel <michal.orzel@arm.com>
To: Julien Grall <julien@xen.org>, xen-devel@lists.xenproject.org
Cc: Stefano Stabellini <sstabellini@kernel.org>,
Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
bertrand.marquis@arm.com
Subject: Re: [PATCH 9/9] xen/arm64: Remove READ/WRITE_SYSREG32 helper macros
Date: Tue, 27 Apr 2021 09:16:14 +0200 [thread overview]
Message-ID: <a37f7d85-dee7-d2f8-9883-1a8004d1ca25@arm.com> (raw)
In-Reply-To: <c318c303-1187-3a64-833b-0684a2dc4312@xen.org>
Hi Jilien,
On 21.04.2021 21:16, Julien Grall wrote:
> Hi Michal,
>
> On 20/04/2021 08:08, Michal Orzel wrote:
>> AArch64 system registers are 64bit whereas AArch32 ones
>> are 32bit or 64bit. MSR/MRS are expecting 64bit values thus
>> we should get rid of helpers READ/WRITE_SYSREG32
>> in favour of using READ/WRITE_SYSREG.
>> We should also use register_t type when reading sysregs
>> which can correspond to uint64_t or uint32_t.
>> Even though many AArch64 sysregs have upper 32bit reserved
>> it does not mean that they can't be widen in the future.
>
> As a general comment, all your commit message contains information about the goal (which is great). But they don't go much in details about the actual changes. I have tried to point out where I think those details would be helpful.
>
>>
>> As there are no other places in the code using READ/WRITE_SYSREG32,
>> remove the helper macros.
>>
>> Signed-off-by: Michal Orzel <michal.orzel@arm.com>
>> ---
>> xen/arch/arm/vcpreg.c | 16 ++++++++++++++++
>> xen/include/asm-arm/arm64/sysregs.h | 5 -----
>> 2 files changed, 16 insertions(+), 5 deletions(-)
>>
>> diff --git a/xen/arch/arm/vcpreg.c b/xen/arch/arm/vcpreg.c
>> index c7f516ee0a..6cb7f3108c 100644
>> --- a/xen/arch/arm/vcpreg.c
>> +++ b/xen/arch/arm/vcpreg.c
>> @@ -48,6 +48,7 @@
>> */
>> /* The name is passed from the upper macro to workaround macro expansion. */
>> +#ifdef CONFIG_ARM_32
>> #define TVM_REG(sz, func, reg...) \
>> static bool func(struct cpu_user_regs *regs, uint##sz##_t *r, bool read) \
>> { \
>> @@ -61,6 +62,21 @@ static bool func(struct cpu_user_regs *regs, uint##sz##_t *r, bool read) \
>> \
>> return true; \
>> }
>> +#else /* CONFIG_ARM_64 */
>> +#define TVM_REG(sz, func, reg...) \
>> +static bool func(struct cpu_user_regs *regs, uint##sz##_t *r, bool read) \
>> +{ \
>> + struct vcpu *v = current; \
>> + bool cache_enabled = vcpu_has_cache_enabled(v); \
>> + \
>> + GUEST_BUG_ON(read); \
>> + WRITE_SYSREG(*r, reg); \
>> + \
>> + p2m_toggle_cache(v, cache_enabled); \
>> + \
>> + return true; \
>> +}
>> +#endif
>
> It would be nice if this change can be explained in the commit message. However, I think we can avoid the duplication by aliasing TVM_REG32() to TVM_REG64() on Arm64.
>
Unfortunately we cannot. This is the only working solution for now.
If we do the alias we will get many errors due to incompatbile pointer type in vreg_emulate_*.
Without a proper change in this functions we can't do that.
I will modify it once I start working on vreg_emulate topic but it requires more investigation.
For now I'd suggest to keep it as it is + explain the change in the commit.
I will push v2 soon.
>> #define TVM_REG32(regname, xreg) TVM_REG(32, vreg_emulate_##regname, xreg)
>> #define TVM_REG64(regname, xreg) TVM_REG(64, vreg_emulate_##regname, xreg)
>> diff --git a/xen/include/asm-arm/arm64/sysregs.h b/xen/include/asm-arm/arm64/sysregs.h
>> index 077fd95fb7..83a1157ac4 100644
>> --- a/xen/include/asm-arm/arm64/sysregs.h
>> +++ b/xen/include/asm-arm/arm64/sysregs.h
>> @@ -86,11 +86,6 @@
>> #endif
>> /* Access to system registers */
>> -
>> -#define READ_SYSREG32(name) ((uint32_t)READ_SYSREG64(name))
>> -
>> -#define WRITE_SYSREG32(v, name) WRITE_SYSREG64((uint64_t)v, name)
>> -
>> #define WRITE_SYSREG64(v, name) do { \
>> uint64_t _r = v; \
>> asm volatile("msr "__stringify(name)", %0" : : "r" (_r)); \
>>
>
> Cheers,
>
Cheers,
Michal
next prev parent reply other threads:[~2021-04-27 7:16 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-20 7:08 [PATCH 0/9] xen/arm64: Get rid of READ/WRITE_SYSREG32 Michal Orzel
2021-04-20 7:08 ` [PATCH 1/9] arm64/vfp: " Michal Orzel
2021-04-20 13:04 ` Julien Grall
2021-04-20 7:08 ` [PATCH 2/9] arm/domain: " Michal Orzel
2021-04-20 13:12 ` Julien Grall
2021-04-21 7:36 ` Michal Orzel
2021-04-21 10:20 ` Julien Grall
2021-04-20 7:08 ` [PATCH 3/9] arm/gic: " Michal Orzel
2021-04-20 13:28 ` Julien Grall
2021-04-21 7:48 ` Michal Orzel
2021-04-21 10:21 ` Julien Grall
2021-04-20 7:08 ` [PATCH 4/9] arm/p2m: " Michal Orzel
2021-04-20 13:31 ` Julien Grall
2021-04-20 7:08 ` [PATCH 5/9] arm/mm: " Michal Orzel
2021-04-20 13:37 ` Julien Grall
2021-04-22 11:47 ` Michal Orzel
2021-04-22 13:40 ` Julien Grall
2021-04-20 7:08 ` [PATCH 6/9] arm/page: " Michal Orzel
2021-04-21 15:11 ` Julien Grall
2021-04-20 7:08 ` [PATCH 7/9] arm/time,vtimer: " Michal Orzel
2021-04-21 16:01 ` Julien Grall
2021-04-20 7:08 ` [PATCH 8/9] arm: Change type of hsr to register_t Michal Orzel
2021-04-21 19:02 ` Julien Grall
2021-04-20 7:08 ` [PATCH 9/9] xen/arm64: Remove READ/WRITE_SYSREG32 helper macros Michal Orzel
2021-04-21 19:16 ` Julien Grall
2021-04-27 7:16 ` Michal Orzel [this message]
2021-04-27 8:30 ` Julien Grall
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