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Commit 0966253d authored by Catalin Marinas's avatar Catalin Marinas
Browse files

kvm: arm64: Convert kvm_set_s2pte_readonly() from inline asm to cmpxchg() 



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: default avatarWill Deacon <will.deacon@arm.com>
Reviewed-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 3bbf7157

arch/arm64/include/asm/kvm_mmu.h

+9 −12
Original line number Diff line number Diff line
@@ -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)