linux-kernel - [RFC PATCH v1 1/8] KVM: selftests: x86: Fix bug in addr_arch

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Message-Id: <20231102155111.28821-2-guang.zeng@intel.com>
Date:   Thu,  2 Nov 2023 23:51:04 +0800
From:   Zeng Guang <guang.zeng@...el.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Shuah Khan <shuah@...nel.org>, Marc Zyngier <maz@...nel.org>,
        Oliver Upton <oliver.upton@...ux.dev>,
        James Morse <james.morse@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Zenghui Yu <yuzenghui@...wei.com>,
        Anup Patel <anup@...infault.org>,
        Atish Patra <atishp@...shpatra.org>,
        David Hildenbrand <david@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.linux.dev, kvm-riscv@...ts.infradead.org,
        linux-riscv@...ts.infradead.org, Zeng Guang <guang.zeng@...el.com>
Subject: [RFC PATCH v1 1/8] KVM: selftests: x86: Fix bug in addr_arch_gva2gpa()

Fix the approach to get page map from gva to gpa.

If gva maps a 4-KByte page, current implementation of addr_arch_gva2gpa()
will obtain wrong page size and cannot derive correct offset from the guest
virtual address.

Meanwhile using HUGEPAGE_MASK(x) to calculate the offset within page
(1G/2M/4K) mistakenly incorporates the upper part of 64-bit canonical
linear address. That will work out improper guest physical address if
translating guest virtual address in supervisor-mode address space.

Signed-off-by: Zeng Guang <guang.zeng@...el.com>
---
 tools/testing/selftests/kvm/lib/x86_64/processor.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index d8288374078e..9f4b8c47edce 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -293,6 +293,7 @@ uint64_t *__vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr,
 	if (vm_is_target_pte(pde, level, PG_LEVEL_2M))
 		return pde;
 
+	*level = PG_LEVEL_4K;
 	return virt_get_pte(vm, pde, vaddr, PG_LEVEL_4K);
 }
 
@@ -496,7 +497,7 @@ vm_paddr_t addr_arch_gva2gpa(struct kvm_vm *vm, vm_vaddr_t gva)
 	 * No need for a hugepage mask on the PTE, x86-64 requires the "unused"
 	 * address bits to be zero.
 	 */
-	return PTE_GET_PA(*pte) | (gva & ~HUGEPAGE_MASK(level));
+	return PTE_GET_PA(*pte) | (gva & (HUGEPAGE_SIZE(level) - 1));
 }
 
 static void kvm_setup_gdt(struct kvm_vm *vm, struct kvm_dtable *dt)
-- 
2.21.3