Re: [PATCH] arm64/mm: Fix __enable_mmu() for new TGRAN range values
From: Marc Zyngier <maz@kernel.org>
Date: 2021-03-08 14:43:00
Also in:
kvmarm, linux-efi, lkml
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
On Fri, 05 Mar 2021 14:36:09 +0000, Anshuman Khandual [off-list ref] wrote:
quoted hunk ↗ jump to hunk
From: James Morse <james.morse@arm.com> 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 <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Marc Zyngier <maz@kernel.org> Cc: James Morse <james.morse@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> 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 Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Anshuman Khandual <redacted> --- arch/arm64/include/asm/sysreg.h | 20 ++++++++++++++------ arch/arm64/kernel/head.S | 6 ++++-- arch/arm64/kvm/reset.c | 23 ++++++++++++----------- drivers/firmware/efi/libstub/arm64-stub.c | 2 +- 4 files changed, 31 insertions(+), 20 deletions(-)diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index dfd4edb..d4a5fca9 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h@@ -796,6 +796,11 @@ #define ID_AA64MMFR0_PARANGE_48 0x5 #define ID_AA64MMFR0_PARANGE_52 0x6 +#define ID_AA64MMFR0_TGRAN_2_SUPPORTED_DEFAULT 0x0 +#define ID_AA64MMFR0_TGRAN_2_SUPPORTED_NONE 0x1 +#define ID_AA64MMFR0_TGRAN_2_SUPPORTED_MIN 0x2 +#define ID_AA64MMFR0_TGRAN_2_SUPPORTED_MAX 0x7
It really feels like we're inventing stuff that the ARM ARM couldn't be bothered to describe. Oh well.
- switch (cpuid_feature_extract_unsigned_field(mmfr0, tgran_2)) {
- default:
- case 1:
+ tgran_2 = cpuid_feature_extract_unsigned_field(mmfr0, tgran_2_shift);
+ if (tgran_2 == ID_AA64MMFR0_TGRAN_2_SUPPORTED_NONE) {
kvm_err("PAGE_SIZE not supported at Stage-2, giving up\n");
return -EINVAL;
- case 0:
+ } else if (tgran_2 == ID_AA64MMFR0_TGRAN_2_SUPPORTED_DEFAULT) {
kvm_debug("PAGE_SIZE supported at Stage-2 (default)\n");
- break;
- case 2:
+ } else if (tgran_2 >= ID_AA64MMFR0_TGRAN_2_SUPPORTED_MIN &&
+ tgran_2 <= ID_AA64MMFR0_TGRAN_2_SUPPORTED_MAX) {
kvm_debug("PAGE_SIZE supported at Stage-2 (advertised)\n");
- break;
+ } else {
+ kvm_err("Unsupported value, giving up\n");
+ return -EINVAL;nit: this doesn't say *what* value is unsupported, and I really preferred the switch-case version, such as this:
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 1f22b36a0eff..d267e4b1aec6 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c@@ -312,15 +312,18 @@ 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);
Otherwise: Acked-by: Marc Zyngier <maz@kernel.org> M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel