linux-kernel - [PATCH 5.4 415/434] KVM: PPC: Book3S HV: Fix regression on big endian hosts

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Date:   Sun, 29 Dec 2019 18:27:48 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Marcus Comstedt <marcus@...pp.se>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: [PATCH 5.4 415/434] KVM: PPC: Book3S HV: Fix regression on big endian hosts

From: Marcus Comstedt <marcus@...pp.se>

commit 228b607d8ea1b7d4561945058d5692709099d432 upstream.

VCPU_CR is the offset of arch.regs.ccr in kvm_vcpu.
arch/powerpc/include/asm/kvm_host.h defines arch.regs as a struct
pt_regs, and arch/powerpc/include/asm/ptrace.h defines the ccr field
of pt_regs as "unsigned long ccr".  Since unsigned long is 64 bits, a
64-bit load needs to be used to load it, unless an endianness specific
correction offset is added to access the desired subpart.  In this
case there is no reason to _not_ use a 64 bit load though.

Fixes: 6c85b7bc637b ("powerpc/kvm: Use UV_RETURN ucall to return to ultravisor")
Cc: stable@...r.kernel.org # v5.4+
Signed-off-by: Marcus Comstedt <marcus@...pp.se>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Link: https://lore.kernel.org/r/20191215094900.46740-1-marcus@mc.pp.se
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/kvm/book3s_hv_rmhandlers.S |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -1117,7 +1117,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
 	ld	r7, VCPU_GPR(R7)(r4)
 	bne	ret_to_ultra
 
-	lwz	r0, VCPU_CR(r4)
+	ld	r0, VCPU_CR(r4)
 	mtcr	r0
 
 	ld	r0, VCPU_GPR(R0)(r4)
@@ -1137,7 +1137,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
  *   R3 = UV_RETURN
  */
 ret_to_ultra:
-	lwz	r0, VCPU_CR(r4)
+	ld	r0, VCPU_CR(r4)
 	mtcr	r0
 
 	ld	r0, VCPU_GPR(R3)(r4)