Re: [PATCH v2 02/20] KVM: selftests: Use the common minimum GPA for page tables on LoongArch

From: Bibo Mao <maobibo@loongson.cn>
To: Sean Christopherson <seanjc@google.com>,
	Marc Zyngier <maz@kernel.org>, Oliver Upton <oupton@kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Tianrui Zhao <zhaotianrui@loongson.cn>,
	Huacai Chen <chenhuacai@kernel.org>,
	Anup Patel <anup@brainfault.org>, Paul Walmsley <pjw@kernel.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Christian Borntraeger <borntraeger@linux.ibm.com>,
	Janosch Frank <frankja@linux.ibm.com>,
	Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Fuad Tabba <fuad.tabba@linux.dev>,
	Joey Gouly <joey.gouly@arm.com>,
	Steffen Eiden <seiden@linux.ibm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>,
	Atish Patra <atish.patra@linux.dev>,
	Alexandre Ghiti <alex@ghiti.fr>,
	David Hildenbrand <david@kernel.org>,
	linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
	kvm@vger.kernel.org, loongarch@lists.linux.dev,
	kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Itaru Kitayama <itaru.kitayama@fujitsu.com>,
	Nicholas Piggin <npiggin@gmail.com>,
	Ritesh Harjani <ritesh.list@gmail.com>
Subject: Re: [PATCH v2 02/20] KVM: selftests: Use the common minimum GPA for page tables on LoongArch
Date: Thu, 3 Sep 2026 09:01:24 +0800	[thread overview]
Message-ID: <170acb36-7542-e6f8-d834-250816ddfbfc@loongson.cn> (raw)
In-Reply-To: <20260902164123.2546762-3-seanjc@google.com>


On 2026/9/3 上午12:41, Sean Christopherson wrote:
> Use the common minimum GPA for page tables (0x180000) on LoongArch instead
> of LoongArch's custom minimum of 0x200000, so that LoongArch can use
> vm_alloc_page_table() instead of open coding a rough equivalent.  There are
> no known reasons why LoongArch can't use a lower, less-aligned minimum.
> The more-aligned value was originally selected to support huge pages for
> the guest, but that only requires the address of the final allocation to be
> aligned, the addresses of page table pages is irrelevant on that front.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>   tools/testing/selftests/kvm/lib/loongarch/processor.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/lib/loongarch/processor.c b/tools/testing/selftests/kvm/lib/loongarch/processor.c
> index 47bbde3e205a..057a77713542 100644
> --- a/tools/testing/selftests/kvm/lib/loongarch/processor.c
> +++ b/tools/testing/selftests/kvm/lib/loongarch/processor.c
> @@ -9,7 +9,6 @@
>   #include "processor.h"
>   #include "ucall_common.h"
>   
> -#define LOONGARCH_PAGE_TABLE_PHYS_MIN		0x200000
>   #define LOONGARCH_GUEST_STACK_VADDR_MIN		0x200000
>   
>   static gpa_t invalid_pgtable[4];
> @@ -57,7 +56,7 @@ void virt_arch_pgd_alloc(struct kvm_vm *vm)
>   	child = table = 0;
>   	for (i = 0; i < vm->mmu.pgtable_levels; i++) {
>   		invalid_pgtable[i] = child;
> -		table = vm_phy_page_alloc(vm, LOONGARCH_PAGE_TABLE_PHYS_MIN,
> +		table = vm_phy_page_alloc(vm, KVM_GUEST_PAGE_TABLE_MIN_PADDR,
>   				vm->memslots[MEM_REGION_PT]);
>   		TEST_ASSERT(table, "Fail to allocate page tale at level %d\n", i);
>   		virt_set_pgtable(vm, table, child);
> 
Reviewed-by: Bibo Mao <maobibo@loongson.cn>


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