linux-kernel - [PATCH] KVM: arm64: Return -EPERM from __pkvm_host_share

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Date:   Wed, 11 Aug 2021 18:36:25 +0100
From:   Quentin Perret <qperret@...gle.com>
To:     Marc Zyngier <maz@...nel.org>, James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Quentin Perret <qperret@...gle.com>,
        Fuad Tabba <tabba@...gle.com>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org
Subject: [PATCH] KVM: arm64: Return -EPERM from __pkvm_host_share_hyp()

Fix the error code returned by __pkvm_host_share_hyp() when the
host attempts to share with EL2 a page that has already been shared with
another entity.

Reported-by: Will Deacon <will@...nel.org>
Signed-off-by: Quentin Perret <qperret@...gle.com>
---
This patch fixes a bug introduced in the stage-2 ownership series which
is already queued in kvmarm/next:

https://lore.kernel.org/lkml/20210809152448.1810400-1-qperret@google.com/

I've starred at this code for hours, but that clearly was not enough. Oh
well ...
---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 8165390d3ec9..6ec695311498 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -404,7 +404,7 @@ int __pkvm_host_share_hyp(u64 pfn)
 	cur = kvm_pgtable_hyp_pte_prot(pte);
 	prot = pkvm_mkstate(PAGE_HYP, PKVM_PAGE_SHARED_BORROWED);
 	if (!check_prot(cur, prot, ~prot))
-		ret = EPERM;
+		ret = -EPERM;
 	goto unlock;
 
 map_shared:
-- 
2.32.0.605.g8dce9f2422-goog