[PATCH v3 01/17] KVM: arm64: Drop is_kernel_in_hyp_mode() from __invalidate_icache_guest_page()

From: Marc Zyngier <maz@kernel.org>
To: kvmarm@lists.linux.dev, kvm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Cc: James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	Zenghui Yu <yuzenghui@huawei.com>,
	Quentin Perret <qperret@google.com>,
	Will Deacon <will@kernel.org>, Fuad Tabba <tabba@google.com>
Subject: [PATCH v3 01/17] KVM: arm64: Drop is_kernel_in_hyp_mode() from __invalidate_icache_guest_page()
Date: Fri,  9 Jun 2023 17:21:44 +0100	[thread overview]
Message-ID: <20230609162200.2024064-2-maz@kernel.org> (raw)
In-Reply-To: <20230609162200.2024064-1-maz@kernel.org>

It is pretty obvious that is_kernel_in_hyp_mode() doesn't make much
sense in the hypervisor part of KVM, and should be reserved to the
kernel side.

However, mem_protect.c::invalidate_icache_guest_page() calls into
__invalidate_icache_guest_page(), which uses is_kernel_in_hyp_mode().
Given that this is part of the pKVM side of the hypervisor, this
helper can only return true.

Nothing goes really bad, but __invalidate_icache_guest_page() could
spell out what the actual check is: we cannot invalidate the cache
if the i-cache is VPIPT and we're running at EL1.

Drop the is_kernel_in_hyp_mode() check for an explicit check against
CurrentEL being EL1 or not.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/include/asm/kvm_mmu.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 27e63c111f78..c8113b931263 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -227,7 +227,8 @@ static inline void __invalidate_icache_guest_page(void *va, size_t size)
 	if (icache_is_aliasing()) {
 		/* any kind of VIPT cache */
 		icache_inval_all_pou();
-	} else if (is_kernel_in_hyp_mode() || !icache_is_vpipt()) {
+	} else if (read_sysreg(CurrentEL) != CurrentEL_EL1 ||
+		   !icache_is_vpipt()) {
 		/* PIPT or VPIPT at EL2 (see comment in __kvm_tlb_flush_vmid_ipa) */
 		icache_inval_pou((unsigned long)va, (unsigned long)va + size);
 	}
-- 
2.34.1

