From 26f55386f964cefa92ab7ccbed68f1a313074215 Mon Sep 17 00:00:00 2001 From: James Morse Date: Wed, 10 Mar 2021 11:23:10 +0530 Subject: arm64/mm: Fix __enable_mmu() for new TGRAN range values As per ARM ARM DDI 0487G.a, when FEAT_LPA2 is implemented, ID_AA64MMFR0_EL1 might contain a range of values to describe supported translation granules (4K and 16K pages sizes in particular) instead of just enabled or disabled values. This changes __enable_mmu() function to handle complete acceptable range of values (depending on whether the field is signed or unsigned) now represented with ID_AA64MMFR0_TGRAN_SUPPORTED_[MIN..MAX] pair. While here, also fix similar situations in EFI stub and KVM as well. Cc: Catalin Marinas Cc: Will Deacon Cc: Marc Zyngier Cc: James Morse Cc: Suzuki K Poulose Cc: Ard Biesheuvel Cc: Mark Rutland Cc: linux-arm-kernel@lists.infradead.org Cc: kvmarm@lists.cs.columbia.edu Cc: linux-efi@vger.kernel.org Cc: linux-kernel@vger.kernel.org Acked-by: Marc Zyngier Signed-off-by: James Morse Signed-off-by: Anshuman Khandual Link: https://lore.kernel.org/r/1615355590-21102-1-git-send-email-anshuman.khandual@arm.com Signed-off-by: Will Deacon --- arch/arm64/kvm/reset.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'arch/arm64/kvm/reset.c') diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c index 47f3f035f3ea..e81c7ec9e102 100644 --- a/arch/arm64/kvm/reset.c +++ b/arch/arm64/kvm/reset.c @@ -311,16 +311,18 @@ int kvm_set_ipa_limit(void) } switch (cpuid_feature_extract_unsigned_field(mmfr0, tgran_2)) { - default: - case 1: + case ID_AA64MMFR0_TGRAN_2_SUPPORTED_NONE: kvm_err("PAGE_SIZE not supported at Stage-2, giving up\n"); return -EINVAL; - case 0: + case ID_AA64MMFR0_TGRAN_2_SUPPORTED_DEFAULT: kvm_debug("PAGE_SIZE supported at Stage-2 (default)\n"); break; - case 2: + case ID_AA64MMFR0_TGRAN_2_SUPPORTED_MIN ... ID_AA64MMFR0_TGRAN_2_SUPPORTED_MAX: kvm_debug("PAGE_SIZE supported at Stage-2 (advertised)\n"); break; + default: + kvm_err("Unsupported value for TGRAN_2, giving up\n"); + return -EINVAL; } kvm_ipa_limit = id_aa64mmfr0_parange_to_phys_shift(parange); -- cgit v1.2.3 From 7d717558dd5ef10d28866750d5c24ff892ea3778 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 11 Mar 2021 10:00:15 +0000 Subject: KVM: arm64: Reject VM creation when the default IPA size is unsupported KVM/arm64 has forever used a 40bit default IPA space, partially due to its 32bit heritage (where the only choice is 40bit). However, there are implementations in the wild that have a *cough* much smaller *cough* IPA space, which leads to a misprogramming of VTCR_EL2, and a guest that is stuck on its first memory access if userspace dares to ask for the default IPA setting (which most VMMs do). Instead, blundly reject the creation of such VM, as we can't satisfy the requirements from userspace (with a one-off warning). Also clarify the boot warning, and document that the VM creation will fail when an unsupported IPA size is provided. Although this is an ABI change, it doesn't really change much for userspace: - the guest couldn't run before this change, but no error was returned. At least userspace knows what is happening. - a memory slot that was accepted because it did fit the default IPA space now doesn't even get a chance to be registered. The other thing that is left doing is to convince userspace to actually use the IPA space setting instead of relying on the antiquated default. Fixes: 233a7cb23531 ("kvm: arm64: Allow tuning the physical address size for VM") Signed-off-by: Marc Zyngier Cc: stable@vger.kernel.org Reviewed-by: Andrew Jones Reviewed-by: Eric Auger Link: https://lore.kernel.org/r/20210311100016.3830038-2-maz@kernel.org --- Documentation/virt/kvm/api.rst | 3 +++ arch/arm64/kvm/reset.c | 12 ++++++++---- 2 files changed, 11 insertions(+), 4 deletions(-) (limited to 'arch/arm64/kvm/reset.c') diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 1a2b5210cdbf..38e327d4b479 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -182,6 +182,9 @@ is dependent on the CPU capability and the kernel configuration. The limit can be retrieved using KVM_CAP_ARM_VM_IPA_SIZE of the KVM_CHECK_EXTENSION ioctl() at run-time. +Creation of the VM will fail if the requested IPA size (whether it is +implicit or explicit) is unsupported on the host. + Please note that configuring the IPA size does not affect the capability exposed by the guest CPUs in ID_AA64MMFR0_EL1[PARange]. It only affects size of the address translated by the stage2 level (guest physical to diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c index 47f3f035f3ea..9d3d09a89894 100644 --- a/arch/arm64/kvm/reset.c +++ b/arch/arm64/kvm/reset.c @@ -324,10 +324,9 @@ int kvm_set_ipa_limit(void) } kvm_ipa_limit = id_aa64mmfr0_parange_to_phys_shift(parange); - WARN(kvm_ipa_limit < KVM_PHYS_SHIFT, - "KVM IPA Size Limit (%d bits) is smaller than default size\n", - kvm_ipa_limit); - kvm_info("IPA Size Limit: %d bits\n", kvm_ipa_limit); + kvm_info("IPA Size Limit: %d bits%s\n", kvm_ipa_limit, + ((kvm_ipa_limit < KVM_PHYS_SHIFT) ? + " (Reduced IPA size, limited VM/VMM compatibility)" : "")); return 0; } @@ -356,6 +355,11 @@ int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type) return -EINVAL; } else { phys_shift = KVM_PHYS_SHIFT; + if (phys_shift > kvm_ipa_limit) { + pr_warn_once("%s using unsupported default IPA limit, upgrade your VMM\n", + current->comm); + return -EINVAL; + } } mmfr0 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1); -- cgit v1.2.3