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Message-ID: <l7txoioo3gntu3lyl542jg3n3wvkqruf2qh33xy7lmr5mjgfq5@iw4wsfdurlc7>
Date: Wed, 15 Oct 2025 21:23:25 +0000
From: Yosry Ahmed <yosry.ahmed@...ux.dev>
To: Jim Mattson <jmattson@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Shuah Khan <shuah@...nel.org>,
Sean Christopherson <seanjc@...gle.com>, Bibo Mao <maobibo@...ngson.cn>,
Huacai Chen <chenhuacai@...nel.org>, Andrew Jones <ajones@...tanamicro.com>,
Claudio Imbrenda <imbrenda@...ux.ibm.com>, "Pratik R. Sampat" <prsampat@....com>,
Kai Huang <kai.huang@...el.com>, Eric Auger <eric.auger@...hat.com>, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH 3/4] KVM: selftests: Add VM_MODE_PXXV57_4K VM mode
On Wed, Sep 17, 2025 at 02:48:39PM -0700, Jim Mattson wrote:
> Add a new VM mode, VM_MODE_PXXV57_4K, to support tests that require
> 5-level paging on x86. This mode sets up a 57-bit virtual address
> space and sets CR4.LA57 in the guest.
>
> Signed-off-by: Jim Mattson <jmattson@...gle.com>
> ---
> .../testing/selftests/kvm/include/kvm_util.h | 1 +
> tools/testing/selftests/kvm/lib/kvm_util.c | 21 +++++++++++++++++
> .../testing/selftests/kvm/lib/x86/processor.c | 23 ++++++++++++-------
> tools/testing/selftests/kvm/lib/x86/vmx.c | 7 +++---
> 4 files changed, 41 insertions(+), 11 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index 23a506d7eca3..b6ea5d966715 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> @@ -175,6 +175,7 @@ enum vm_guest_mode {
> VM_MODE_P40V48_16K,
> VM_MODE_P40V48_64K,
> VM_MODE_PXXV48_4K, /* For 48bits VA but ANY bits PA */
> + VM_MODE_PXXV57_4K, /* For 48bits VA but ANY bits PA */
> VM_MODE_P47V64_4K,
> VM_MODE_P44V64_4K,
> VM_MODE_P36V48_4K,
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index c3f5142b0a54..6b0e499c6e91 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -232,6 +232,7 @@ const char *vm_guest_mode_string(uint32_t i)
> [VM_MODE_P40V48_16K] = "PA-bits:40, VA-bits:48, 16K pages",
> [VM_MODE_P40V48_64K] = "PA-bits:40, VA-bits:48, 64K pages",
> [VM_MODE_PXXV48_4K] = "PA-bits:ANY, VA-bits:48, 4K pages",
> + [VM_MODE_PXXV57_4K] = "PA-bits:ANY, VA-bits:57, 4K pages",
> [VM_MODE_P47V64_4K] = "PA-bits:47, VA-bits:64, 4K pages",
> [VM_MODE_P44V64_4K] = "PA-bits:44, VA-bits:64, 4K pages",
> [VM_MODE_P36V48_4K] = "PA-bits:36, VA-bits:48, 4K pages",
> @@ -259,6 +260,7 @@ const struct vm_guest_mode_params vm_guest_mode_params[] = {
> [VM_MODE_P40V48_16K] = { 40, 48, 0x4000, 14 },
> [VM_MODE_P40V48_64K] = { 40, 48, 0x10000, 16 },
> [VM_MODE_PXXV48_4K] = { 0, 0, 0x1000, 12 },
> + [VM_MODE_PXXV57_4K] = { 0, 0, 0x1000, 12 },
> [VM_MODE_P47V64_4K] = { 47, 64, 0x1000, 12 },
> [VM_MODE_P44V64_4K] = { 44, 64, 0x1000, 12 },
> [VM_MODE_P36V48_4K] = { 36, 48, 0x1000, 12 },
> @@ -358,6 +360,25 @@ struct kvm_vm *____vm_create(struct vm_shape shape)
> vm->va_bits = 48;
> #else
> TEST_FAIL("VM_MODE_PXXV48_4K not supported on non-x86 platforms");
> +#endif
> + break;
> + case VM_MODE_PXXV57_4K:
> +#ifdef __x86_64__
> + kvm_get_cpu_address_width(&vm->pa_bits, &vm->va_bits);
> + kvm_init_vm_address_properties(vm);
> + /*
> + * For 5-level paging, KVM requires LA57 to be enabled, which
> + * requires a 57-bit virtual address space.
> + */
> + TEST_ASSERT(vm->va_bits == 57,
> + "Linear address width (%d bits) not supported for VM_MODE_PXXV57_4K",
> + vm->va_bits);
> + pr_debug("Guest physical address width detected: %d\n",
> + vm->pa_bits);
> + vm->pgtable_levels = 5;
> + vm->va_bits = 57;
We assert that vm->va_bits is 57, and then we set it here again. Seems
like we're doing the same for VM_MODE_PXXV48_4K too.
> +#else
> + TEST_FAIL("VM_MODE_PXXV57_4K not supported on non-x86 platforms");
> #endif
> break;
> case VM_MODE_P47V64_4K:
> diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
> index 433365c8196d..d566190ea488 100644
> --- a/tools/testing/selftests/kvm/lib/x86/processor.c
> +++ b/tools/testing/selftests/kvm/lib/x86/processor.c
> @@ -124,10 +124,11 @@ bool kvm_is_tdp_enabled(void)
>
> void virt_arch_pgd_alloc(struct kvm_vm *vm)
> {
> - TEST_ASSERT(vm->mode == VM_MODE_PXXV48_4K, "Attempt to use "
> - "unknown or unsupported guest mode, mode: 0x%x", vm->mode);
> + TEST_ASSERT(vm->mode == VM_MODE_PXXV48_4K ||
> + vm->mode == VM_MODE_PXXV57_4K,
> + "Unknown or unsupported guest mode: 0x%x", vm->mode);
>
> - /* If needed, create page map l4 table. */
> + /* If needed, create the top-level page table. */
> if (!vm->pgd_created) {
> vm->pgd = vm_alloc_page_table(vm);
> vm->pgd_created = true;
> @@ -187,8 +188,9 @@ void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, int level)
> uint64_t *pte = &vm->pgd;
> int current_level;
>
> - TEST_ASSERT(vm->mode == VM_MODE_PXXV48_4K,
> - "Unknown or unsupported guest mode, mode: 0x%x", vm->mode);
> + TEST_ASSERT(vm->mode == VM_MODE_PXXV48_4K ||
> + vm->mode == VM_MODE_PXXV57_4K,
> + "Unknown or unsupported guest mode: 0x%x", vm->mode);
>
> TEST_ASSERT((vaddr % pg_size) == 0,
> "Virtual address not aligned,\n"
> @@ -279,8 +281,9 @@ uint64_t *__vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr,
> TEST_ASSERT(*level >= PG_LEVEL_NONE && *level < PG_LEVEL_NUM,
> "Invalid PG_LEVEL_* '%d'", *level);
>
> - TEST_ASSERT(vm->mode == VM_MODE_PXXV48_4K, "Attempt to use "
> - "unknown or unsupported guest mode, mode: 0x%x", vm->mode);
> + TEST_ASSERT(vm->mode == VM_MODE_PXXV48_4K ||
> + vm->mode == VM_MODE_PXXV57_4K,
> + "Unknown or unsupported guest mode: 0x%x", vm->mode);
> TEST_ASSERT(sparsebit_is_set(vm->vpages_valid,
> (vaddr >> vm->page_shift)),
> "Invalid virtual address, vaddr: 0x%lx",
> @@ -481,7 +484,9 @@ static void vcpu_init_sregs(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
> {
> struct kvm_sregs sregs;
>
> - TEST_ASSERT_EQ(vm->mode, VM_MODE_PXXV48_4K);
> + TEST_ASSERT(vm->mode == VM_MODE_PXXV48_4K ||
> + vm->mode == VM_MODE_PXXV57_4K,
> + "Unknown or unsupported guest mode: 0x%x", vm->mode);
>
> /* Set mode specific system register values. */
> vcpu_sregs_get(vcpu, &sregs);
> @@ -495,6 +500,8 @@ static void vcpu_init_sregs(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
> sregs.cr4 |= X86_CR4_PAE | X86_CR4_OSFXSR;
> if (kvm_cpu_has(X86_FEATURE_XSAVE))
> sregs.cr4 |= X86_CR4_OSXSAVE;
> + if (vm->pgtable_levels == 5)
> + sregs.cr4 |= X86_CR4_LA57;
> sregs.efer |= (EFER_LME | EFER_LMA | EFER_NX);
>
> kvm_seg_set_unusable(&sregs.ldt);
> diff --git a/tools/testing/selftests/kvm/lib/x86/vmx.c b/tools/testing/selftests/kvm/lib/x86/vmx.c
> index d4d1208dd023..1b6d4a007798 100644
> --- a/tools/testing/selftests/kvm/lib/x86/vmx.c
> +++ b/tools/testing/selftests/kvm/lib/x86/vmx.c
> @@ -401,11 +401,12 @@ void __nested_pg_map(struct vmx_pages *vmx, struct kvm_vm *vm,
> struct eptPageTableEntry *pt = vmx->eptp_hva, *pte;
> uint16_t index;
>
> - TEST_ASSERT(vm->mode == VM_MODE_PXXV48_4K, "Attempt to use "
> - "unknown or unsupported guest mode, mode: 0x%x", vm->mode);
> + TEST_ASSERT(vm->mode == VM_MODE_PXXV48_4K ||
> + vm->mode == VM_MODE_PXXV57_4K,
> + "Unknown or unsupported guest mode: 0x%x", vm->mode);
>
> TEST_ASSERT((nested_paddr >> 48) == 0,
> - "Nested physical address 0x%lx requires 5-level paging",
> + "Nested physical address 0x%lx is > 48-bits and requires 5-level EPT",
Shouldn't this assertion be updated now? We technically support 5-level
EPT so it should only fire if the mode is VM_MODE_PXXV48_4K. Maybe we
should use vm->va_bits?
> nested_paddr);
> TEST_ASSERT((nested_paddr % page_size) == 0,
> "Nested physical address not on page boundary,\n"
> --
> 2.51.0.470.ga7dc726c21-goog
>
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