linux-kernel - Re: [PATCH v8 3/9] KVM: arm64: Move hyp_symbol

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Message-ID: <3010dfe9-f423-1e28-d89f-0731ae52a08b@arm.com>
Date:   Mon, 8 Apr 2019 09:12:24 +0530
From:   Amit Daniel Kachhap <amit.kachhap@....com>
To:     Dave Martin <Dave.Martin@....com>
Cc:     linux-arm-kernel@...ts.infradead.org,
        Marc Zyngier <marc.zyngier@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Kristina Martsenko <kristina.martsenko@....com>,
        kvmarm@...ts.cs.columbia.edu,
        Ramana Radhakrishnan <ramana.radhakrishnan@....com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 3/9] KVM: arm64: Move hyp_symbol_addr to fix dependency

Hi,

On 4/5/19 4:32 PM, Dave Martin wrote:
> On Tue, Apr 02, 2019 at 07:57:11AM +0530, Amit Daniel Kachhap wrote:
>> Currently hyp_symbol_addr is placed in kvm_mmu.h which is mostly
>> used by __hyp_this_cpu_ptr in kvm_asm.h but it cannot include
>> kvm_mmu.h directly as kvm_mmu.h uses kvm_ksym_ref which is
>> defined inside kvm_asm.h. Hence, hyp_symbol_addr is moved inside
>> kvm_asm.h to fix this dependency on each other.
>>
>> Also, hyp_symbol_addr corresponding counterpart, kvm_ksym_ref,
>> is already in kvm_asm.h, making it more sensible to move
>> kvm_symbol_addr to the same file.
>>
>> Suggested by: James Morse <james.morse@....com>
>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@....com>
>> Reviewed-by: Julien Thierry <julien.thierry@....com>
>> Cc: Marc Zyngier <marc.zyngier@....com>
>> Cc: Christoffer Dall <christoffer.dall@....com>
>> Cc: kvmarm@...ts.cs.columbia.edu
>> ---
>>
>> Changes since v7:
>> * Slight change in commit message [Julien Thierry].
>>
>>   arch/arm64/include/asm/kvm_asm.h | 20 ++++++++++++++++++++
>>   arch/arm64/include/asm/kvm_mmu.h | 20 --------------------
>>   2 files changed, 20 insertions(+), 20 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
>> index f5b79e9..57a07e8 100644
>> --- a/arch/arm64/include/asm/kvm_asm.h
>> +++ b/arch/arm64/include/asm/kvm_asm.h
>> @@ -80,6 +80,26 @@ extern void __vgic_v3_init_lrs(void);
>>   
>>   extern u32 __kvm_get_mdcr_el2(void);
>>   
>> +/*
>> + * Obtain the PC-relative address of a kernel symbol
>> + * s: symbol
>> + *
>> + * The goal of this macro is to return a symbol's address based on a
>> + * PC-relative computation, as opposed to a loading the VA from a
>> + * constant pool or something similar. This works well for HYP, as an
>> + * absolute VA is guaranteed to be wrong. Only use this if trying to
>> + * obtain the address of a symbol (i.e. not something you obtained by
>> + * following a pointer).
>> + */
>> +#define hyp_symbol_addr(s)						\
>> +	({								\
>> +		typeof(s) *addr;					\
>> +		asm("adrp	%0, %1\n"				\
>> +		    "add	%0, %0, :lo12:%1\n"			\
>> +		    : "=r" (addr) : "S" (&s));				\
>> +		addr;							\
>> +	})
>> +
> 
> Do we need to include <asm/kvm_asm.h> in vgic-v2-cpuif-proxy.c now?
Yes asm/kvm_asm.h should be included now.
> 
> Otherwise,
> 
> Reviewed-by: Dave Martin <Dave.Martin@....com>
Thanks,
Amit D
>