From: Catalin Marinas <catalin.marinas@arm.com>
Date: Thu, 6 Jul 2017 11:46:39 +0100
Subject: kvm: arm64: Convert kvm_set_s2pte_readonly() from inline asm to
cmpxchg()
Git-commit: 0966253d7ccddc42a5211b3488bb4f202c04de1b
Patch-mainline: v4.14-rc1
References: bsc#1108010
To take advantage of the LSE atomic instructions and also make the code
cleaner, convert the kvm_set_s2pte_readonly() function to use the more
generic cmpxchg().
Cc: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
arch/arm64/include/asm/kvm_mmu.h | 21 +++++++++------------
1 file changed, 9 insertions(+), 12 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index a89cc22abadc..672c8684d5c2 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -175,18 +175,15 @@ static inline pmd_t kvm_s2pmd_mkwrite(pmd_t pmd)
static inline void kvm_set_s2pte_readonly(pte_t *pte)
{
- pteval_t pteval;
- unsigned long tmp;
-
- asm volatile("// kvm_set_s2pte_readonly\n"
- " prfm pstl1strm, %2\n"
- "1: ldxr %0, %2\n"
- " and %0, %0, %3 // clear PTE_S2_RDWR\n"
- " orr %0, %0, %4 // set PTE_S2_RDONLY\n"
- " stxr %w1, %0, %2\n"
- " cbnz %w1, 1b\n"
- : "=&r" (pteval), "=&r" (tmp), "+Q" (pte_val(*pte))
- : "L" (~PTE_S2_RDWR), "L" (PTE_S2_RDONLY));
+ pteval_t old_pteval, pteval;
+
+ pteval = READ_ONCE(pte_val(*pte));
+ do {
+ old_pteval = pteval;
+ pteval &= ~PTE_S2_RDWR;
+ pteval |= PTE_S2_RDONLY;
+ pteval = cmpxchg_relaxed(&pte_val(*pte), old_pteval, pteval);
+ } while (pteval != old_pteval);
}
static inline bool kvm_s2pte_readonly(pte_t *pte)
--
2.11.0