linux-kernel - [PATCH v3 01/29] KVM: arm64: Add a new function to donate memory with prot

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Message-ID: <20250728175316.3706196-2-smostafa@google.com>
Date: Mon, 28 Jul 2025 17:52:48 +0000
From: Mostafa Saleh <smostafa@...gle.com>
To: linux-kernel@...r.kernel.org, kvmarm@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, iommu@...ts.linux.dev
Cc: maz@...nel.org, oliver.upton@...ux.dev, joey.gouly@....com, 
	suzuki.poulose@....com, yuzenghui@...wei.com, catalin.marinas@....com, 
	will@...nel.org, robin.murphy@....com, jean-philippe@...aro.org, 
	qperret@...gle.com, tabba@...gle.com, jgg@...pe.ca, mark.rutland@....com, 
	praan@...gle.com, Mostafa Saleh <smostafa@...gle.com>
Subject: [PATCH v3 01/29] KVM: arm64: Add a new function to donate memory with prot

Soon, IOMMU drivers running in the hypervisor might interact with
non-coherent devices, so it needs a mechanism to map memory as
non cacheable.
Add ___pkvm_host_donate_hyp() which accepts a new argument for prot,
so the driver can add KVM_PGTABLE_PROT_NORMAL_NC.

Signed-off-by: Mostafa Saleh <smostafa@...gle.com>
---
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  1 +
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 11 +++++++++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
index 5f9d56754e39..52d7ee91e18c 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
@@ -36,6 +36,7 @@ int __pkvm_prot_finalize(void);
 int __pkvm_host_share_hyp(u64 pfn);
 int __pkvm_host_unshare_hyp(u64 pfn);
 int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages);
+int ___pkvm_host_donate_hyp(u64 pfn, u64 nr_pages, enum kvm_pgtable_prot prot);
 int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages);
 int __pkvm_host_share_ffa(u64 pfn, u64 nr_pages);
 int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages);
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 8957734d6183..861e448183fd 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -769,13 +769,15 @@ int __pkvm_host_unshare_hyp(u64 pfn)
 	return ret;
 }
 
-int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages)
+int ___pkvm_host_donate_hyp(u64 pfn, u64 nr_pages, enum kvm_pgtable_prot prot)
 {
 	u64 phys = hyp_pfn_to_phys(pfn);
 	u64 size = PAGE_SIZE * nr_pages;
 	void *virt = __hyp_va(phys);
 	int ret;
 
+	WARN_ON(prot & KVM_PGTABLE_PROT_X);
+
 	host_lock_component();
 	hyp_lock_component();
 
@@ -787,7 +789,7 @@ int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages)
 		goto unlock;
 
 	__hyp_set_page_state_range(phys, size, PKVM_PAGE_OWNED);
-	WARN_ON(pkvm_create_mappings_locked(virt, virt + size, PAGE_HYP));
+	WARN_ON(pkvm_create_mappings_locked(virt, virt + size, prot));
 	WARN_ON(host_stage2_set_owner_locked(phys, size, PKVM_ID_HYP));
 
 unlock:
@@ -797,6 +799,11 @@ int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages)
 	return ret;
 }
 
+int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages)
+{
+	return ___pkvm_host_donate_hyp(pfn, nr_pages, PAGE_HYP);
+}
+
 int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages)
 {
 	u64 phys = hyp_pfn_to_phys(pfn);
-- 
2.50.1.552.g942d659e1b-goog