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Message-ID: <e14529dd-a517-afcb-24f3-198dc8ebb364@kernel.org>
Date: Mon, 29 Jul 2019 10:46:16 +0100
From: Marc Zyngier <maz@...nel.org>
To: Matteo Croce <mcroce@...hat.com>,
linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu
Cc: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: arm64: mark expected switch fall-through
On 28/07/2019 23:53, Matteo Croce wrote:
> Mark switch cases where we are expecting to fall through,
> fixes the following warning:
>
> In file included from ./arch/arm64/include/asm/kvm_emulate.h:19,
> from arch/arm64/kvm/regmap.c:13:
> arch/arm64/kvm/regmap.c: In function ‘vcpu_write_spsr32’:
> ./arch/arm64/include/asm/kvm_hyp.h:31:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
> asm volatile(ALTERNATIVE(__msr_s(r##nvh, "%x0"), \
> ^~~
> ./arch/arm64/include/asm/kvm_hyp.h:46:31: note: in expansion of macro ‘write_sysreg_elx’
> #define write_sysreg_el1(v,r) write_sysreg_elx(v, r, _EL1, _EL12)
> ^~~~~~~~~~~~~~~~
> arch/arm64/kvm/regmap.c:180:3: note: in expansion of macro ‘write_sysreg_el1’
> write_sysreg_el1(v, SYS_SPSR);
> ^~~~~~~~~~~~~~~~
> arch/arm64/kvm/regmap.c:181:2: note: here
> case KVM_SPSR_ABT:
> ^~~~
> In file included from ./arch/arm64/include/asm/cputype.h:132,
> from ./arch/arm64/include/asm/cache.h:8,
> from ./include/linux/cache.h:6,
> from ./include/linux/printk.h:9,
> from ./include/linux/kernel.h:15,
> from ./include/asm-generic/bug.h:18,
> from ./arch/arm64/include/asm/bug.h:26,
> from ./include/linux/bug.h:5,
> from ./include/linux/mmdebug.h:5,
> from ./include/linux/mm.h:9,
> from arch/arm64/kvm/regmap.c:11:
> ./arch/arm64/include/asm/sysreg.h:837:2: warning: this statement may fall through [-Wimplicit-fallthrough=]
> asm volatile("msr " __stringify(r) ", %x0" \
> ^~~
> arch/arm64/kvm/regmap.c:182:3: note: in expansion of macro ‘write_sysreg’
> write_sysreg(v, spsr_abt);
> ^~~~~~~~~~~~
> arch/arm64/kvm/regmap.c:183:2: note: here
> case KVM_SPSR_UND:
> ^~~~
> In file included from ./arch/arm64/include/asm/cputype.h:132,
> from ./arch/arm64/include/asm/cache.h:8,
> from ./include/linux/cache.h:6,
> from ./include/linux/printk.h:9,
> from ./include/linux/kernel.h:15,
> from ./include/asm-generic/bug.h:18,
> from ./arch/arm64/include/asm/bug.h:26,
> from ./include/linux/bug.h:5,
> from ./include/linux/mmdebug.h:5,
> from ./include/linux/mm.h:9,
> from arch/arm64/kvm/regmap.c:11:
> ./arch/arm64/include/asm/sysreg.h:837:2: warning: this statement may fall through [-Wimplicit-fallthrough=]
> asm volatile("msr " __stringify(r) ", %x0" \
> ^~~
> arch/arm64/kvm/regmap.c:184:3: note: in expansion of macro ‘write_sysreg’
> write_sysreg(v, spsr_und);
> ^~~~~~~~~~~~
> arch/arm64/kvm/regmap.c:185:2: note: here
> case KVM_SPSR_IRQ:
> ^~~~
> In file included from ./arch/arm64/include/asm/cputype.h:132,
> from ./arch/arm64/include/asm/cache.h:8,
> from ./include/linux/cache.h:6,
> from ./include/linux/printk.h:9,
> from ./include/linux/kernel.h:15,
> from ./include/asm-generic/bug.h:18,
> from ./arch/arm64/include/asm/bug.h:26,
> from ./include/linux/bug.h:5,
> from ./include/linux/mmdebug.h:5,
> from ./include/linux/mm.h:9,
> from arch/arm64/kvm/regmap.c:11:
> ./arch/arm64/include/asm/sysreg.h:837:2: warning: this statement may fall through [-Wimplicit-fallthrough=]
> asm volatile("msr " __stringify(r) ", %x0" \
> ^~~
> arch/arm64/kvm/regmap.c:186:3: note: in expansion of macro ‘write_sysreg’
> write_sysreg(v, spsr_irq);
> ^~~~~~~~~~~~
> arch/arm64/kvm/regmap.c:187:2: note: here
> case KVM_SPSR_FIQ:
> ^~~~
>
> Signed-off-by: Matteo Croce <mcroce@...hat.com>
> ---
> arch/arm64/kvm/regmap.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/arm64/kvm/regmap.c b/arch/arm64/kvm/regmap.c
> index 0d60e4f0af66..b376b2fdbf51 100644
> --- a/arch/arm64/kvm/regmap.c
> +++ b/arch/arm64/kvm/regmap.c
> @@ -178,12 +178,16 @@ void vcpu_write_spsr32(struct kvm_vcpu *vcpu, unsigned long v)
> switch (spsr_idx) {
> case KVM_SPSR_SVC:
> write_sysreg_el1(v, SYS_SPSR);
> + /* fallthrough */
> case KVM_SPSR_ABT:
> write_sysreg(v, spsr_abt);
> + /* fallthrough */
> case KVM_SPSR_UND:
> write_sysreg(v, spsr_und);
> + /* fallthrough */
> case KVM_SPSR_IRQ:
> write_sysreg(v, spsr_irq);
> + /* fallthrough */
> case KVM_SPSR_FIQ:
> write_sysreg(v, spsr_fiq);
> }
>
That's absolutely the *WRONG* fix. Please see [1] for the real thing.
Thanks,
M.
[1]
https://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git/commit/?id=3d584a3c85d6fe2cf878f220d4ad7145e7f89218
--
Jazz is not dead, it just smells funny...
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