linux-kernel - [PATCH v5 6/9] KVM: Add a helper function to check if a gpa is in writable memselot

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Message-Id: <20250829-pmu_event_info-v5-6-9dca26139a33@rivosinc.com>
Date: Fri, 29 Aug 2025 07:41:07 -0700
From: Atish Patra <atishp@...osinc.com>
To: Anup Patel <anup@...infault.org>, Will Deacon <will@...nel.org>, 
 Mark Rutland <mark.rutland@....com>, 
 Paul Walmsley <paul.walmsley@...ive.com>, 
 Palmer Dabbelt <palmer@...belt.com>, 
 Mayuresh Chitale <mchitale@...tanamicro.com>
Cc: linux-riscv@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, kvm@...r.kernel.org, 
 kvm-riscv@...ts.infradead.org, Atish Patra <atishp@...osinc.com>, 
 Sean Christopherson <seanjc@...gle.com>
Subject: [PATCH v5 6/9] KVM: Add a helper function to check if a gpa is in
 writable memselot

The arch specific code may need to know if a particular gpa is valid and
writable for the shared memory between the host and the guest. Currently,
there are few places where it is used in RISC-V implementation. Given the
nature of the function it may be used for other architectures.
Hence, a common helper function is added.

Suggested-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Atish Patra <atishp@...osinc.com>
---
 include/linux/kvm_host.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 15656b7fba6c..eec5cbbcb4b3 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1892,6 +1892,14 @@ static inline bool kvm_is_gpa_in_memslot(struct kvm *kvm, gpa_t gpa)
 	return !kvm_is_error_hva(hva);
 }
 
+static inline bool kvm_is_gpa_in_writable_memslot(struct kvm *kvm, gpa_t gpa)
+{
+	bool writable;
+	unsigned long hva = gfn_to_hva_prot(kvm, gpa_to_gfn(gpa), &writable);
+
+	return !kvm_is_error_hva(hva) && writable;
+}
+
 static inline void kvm_gpc_mark_dirty_in_slot(struct gfn_to_pfn_cache *gpc)
 {
 	lockdep_assert_held(&gpc->lock);

-- 
2.43.0