FAILED: patch "[PATCH] arm64: KVM: regmap: Fix unexpected switch fall-through" failed to apply to 4.19-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 3d584a3c85d6fe2cf878f220d4ad7145e7f89218 Mon Sep 17 00:00:00 2001
From: Anders Roxell <anders.roxell@linaro.org>
Date: Fri, 26 Jul 2019 13:27:05 +0200
Subject: [PATCH] arm64: KVM: regmap: Fix unexpected switch fall-through
MIME-Version: 1.0
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Content-Transfer-Encoding: 8bit

When fall-through warnings was enabled by default, commit d93512ef0f0e
("Makefile: Globally enable fall-through warning"), the following
warnings was starting to show up:

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:
  ^~~~

Rework to add a 'break;' in the swich-case since it didn't have that,
leading to an interresting set of bugs.

Cc: stable@vger.kernel.org # v4.17+
Fixes: a892819560c4 ("KVM: arm64: Prepare to handle deferred save/restore of 32-bit registers")
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
[maz: reworked commit message, fixed stable range]
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/arch/arm64/kvm/regmap.c b/arch/arm64/kvm/regmap.c
index 0d60e4f0af66..a900181e3867 100644
--- a/arch/arm64/kvm/regmap.c
+++ b/arch/arm64/kvm/regmap.c
@@ -178,13 +178,18 @@ void vcpu_write_spsr32(struct kvm_vcpu *vcpu, unsigned long v)
 	switch (spsr_idx) {
 	case KVM_SPSR_SVC:
 		write_sysreg_el1(v, SYS_SPSR);
+		break;
 	case KVM_SPSR_ABT:
 		write_sysreg(v, spsr_abt);
+		break;
 	case KVM_SPSR_UND:
 		write_sysreg(v, spsr_und);
+		break;
 	case KVM_SPSR_IRQ:
 		write_sysreg(v, spsr_irq);
+		break;
 	case KVM_SPSR_FIQ:
 		write_sysreg(v, spsr_fiq);
+		break;
 	}
 }