diff mbox series

[05/89] KVM: arm64: Extend comment in has_vhe()

Message ID	20220519134204.5379-6-will@kernel.org (mailing list archive)
State	New, archived
Headers	show Return-Path: <kvm-owner@kernel.org> From: Will Deacon <will@kernel.org> To: kvmarm@lists.cs.columbia.edu Cc: Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>, Sean Christopherson <seanjc@google.com>, Alexandru Elisei <alexandru.elisei@arm.com>, Andy Lutomirski <luto@amacapital.net>, Catalin Marinas <catalin.marinas@arm.com>, James Morse <james.morse@arm.com>, Chao Peng <chao.p.peng@linux.intel.com>, Quentin Perret <qperret@google.com>, Suzuki K Poulose <suzuki.poulose@arm.com>, Michael Roth <michael.roth@amd.com>, Mark Rutland <mark.rutland@arm.com>, Fuad Tabba <tabba@google.com>, Oliver Upton <oupton@google.com>, Marc Zyngier <maz@kernel.org>, kernel-team@android.com, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, David Brazdil <dbrazdil@google.com> Subject: [PATCH 05/89] KVM: arm64: Extend comment in has_vhe() Date: Thu, 19 May 2022 14:40:40 +0100 Message-Id: <20220519134204.5379-6-will@kernel.org> In-Reply-To: <20220519134204.5379-1-will@kernel.org> References: <20220519134204.5379-1-will@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	KVM: arm64: Base support for the pKVM hypervisor at EL2 \| expand [00/89] KVM: arm64: Base support for the pKVM hypervisor at EL2 [01/89] KVM: arm64: Handle all ID registers trapped for a protected VM [02/89] KVM: arm64: Remove redundant hyp_assert_lock_held() assertions [03/89] KVM: arm64: Return error from kvm_arch_init_vm() on allocation failure [04/89] KVM: arm64: Ignore 'kvm-arm.mode=protected' when using VHE [05/89] KVM: arm64: Extend comment in has_vhe() [06/89] KVM: arm64: Drop stale comment [07/89] KVM: arm64: Move hyp refcount manipulation helpers [08/89] KVM: arm64: Back hyp_vmemmap for all of memory [09/89] KVM: arm64: Unify identifiers used to distinguish host and hypervisor [10/89] KVM: arm64: Implement do_donate() helper for donating memory [11/89] KVM: arm64: Prevent the donation of no-map pages [12/89] KVM: arm64: Add helpers to pin memory shared with hyp [13/89] KVM: arm64: Include asm/kvm_mmu.h in nvhe/mem_protect.h [14/89] KVM: arm64: Add hyp_spinlock_t static initializer [15/89] KVM: arm64: Introduce shadow VM state at EL2 [16/89] KVM: arm64: Instantiate VM shadow data from EL1 [17/89] KVM: arm64: Make hyp stage-1 refcnt correct on the whole range [18/89] KVM: arm64: Factor out private range VA allocation [19/89] KVM: arm64: Add pcpu fixmap infrastructure at EL2 [20/89] KVM: arm64: Provide I-cache invalidation by VA at EL2 [21/89] KVM: arm64: Allow non-coallescable pages in a hyp_pool [22/89] KVM: arm64: Add generic hyp_memcache helpers [23/89] KVM: arm64: Instantiate guest stage-2 page-tables at EL2 [24/89] KVM: arm64: Return guest memory from EL2 via dedicated teardown memcache [25/89] KVM: arm64: Add flags to struct hyp_page [26/89] KVM: arm64: Provide a hypercall for the host to reclaim guest memory [27/89] KVM: arm64: Extend memory sharing to allow host-to-guest transitions [28/89] KVM: arm64: Consolidate stage-2 init in one function [29/89] KVM: arm64: Check for PTE validity when checking for executable/cacheable [30/89] KVM: arm64: Do not allow memslot changes after first VM run under pKVM [31/89] KVM: arm64: Disallow dirty logging and RO memslots with pKVM [32/89] KVM: arm64: Use the shadow vCPU structure in handle___kvm_vcpu_run() [33/89] KVM: arm64: Handle guest stage-2 page-tables entirely at EL2 [34/89] KVM: arm64: Don't access kvm_arm_hyp_percpu_base at EL1 [35/89] KVM: arm64: Unmap kvm_arm_hyp_percpu_base from the host [36/89] KVM: arm64: Maintain a copy of 'kvm_arm_vmid_bits' at EL2 [37/89] KVM: arm64: Explicitly map kvm_vgic_global_state at EL2 [38/89] KVM: arm64: Don't map host sections in pkvm [39/89] KVM: arm64: Extend memory donation to allow host-to-guest transitions [40/89] KVM: arm64: Split up nvhe/fixed_config.h [41/89] KVM: arm64: Make vcpu_{read,write}_sys_reg available to HYP code [42/89] KVM: arm64: Simplify vgic-v3 hypercalls [43/89] KVM: arm64: Add the {flush,sync}_vgic_state() primitives [44/89] KVM: arm64: Introduce predicates to check for protected state [45/89] KVM: arm64: Add the {flush,sync}_timer_state() primitives [46/89] KVM: arm64: Introduce the pkvm_vcpu_{load,put} hypercalls [47/89] KVM: arm64: Add current vcpu and shadow_state lookup primitive [48/89] KVM: arm64: Skip __kvm_adjust_pc() for protected vcpus [49/89] KVM: arm64: Add hyp per_cpu variable to track current physical cpu number [50/89] KVM: arm64: Ensure that TLBs and I-cache are private to each vcpu [51/89] KVM: arm64: Introduce per-EC entry/exit handlers [52/89] KVM: arm64: Introduce lazy-ish state sync for non-protected VMs [53/89] KVM: arm64: Lazy host FP save/restore [54/89] KVM: arm64: Reduce host/shadow vcpu state copying [55/89] KVM: arm64: Do not pass the vcpu to __pkvm_host_map_guest() [56/89] KVM: arm64: Check directly whether the vcpu is protected [57/89] KVM: arm64: Trap debug break and watch from guest [58/89] KVM: arm64: Restrict protected VM capabilities [59/89] KVM: arm64: Do not support MTE for protected VMs [60/89] KVM: arm64: Refactor reset_mpidr to extract its computation [61/89] KVM: arm64: Reset sysregs for protected VMs [62/89] KVM: arm64: Move pkvm_vcpu_init_traps to shadow vcpu init [63/89] KVM: arm64: Fix initializing traps in protected mode [64/89] KVM: arm64: Advertise GICv3 sysreg interface to protected guests [65/89] KVM: arm64: Force injection of a data abort on NISV MMIO exit [66/89] KVM: arm64: Donate memory to protected guests [67/89] KVM: arm64: Add EL2 entry/exit handlers for pKVM guests [68/89] KVM: arm64: Move vgic state between host and shadow vcpu structures [69/89] KVM: arm64: Do not update virtual timer state for protected VMs [70/89] KVM: arm64: Refactor kvm_vcpu_enable_ptrauth() for hyp use [71/89] KVM: arm64: Initialize shadow vm state at hyp [72/89] KVM: arm64: Track the SVE state in the shadow vcpu [73/89] KVM: arm64: Add HVC handling for protected guests at EL2 [74/89] KVM: arm64: Move pstate reset values to kvm_arm.h [75/89] KVM: arm64: Move some kvm_psci functions to a shared header [76/89] KVM: arm64: Factor out vcpu_reset code for core registers and PSCI [77/89] KVM: arm64: Handle PSCI for protected VMs in EL2 [78/89] KVM: arm64: Don't expose TLBI hypercalls after de-privilege [79/89] KVM: arm64: Add is_pkvm_initialized() helper [80/89] KVM: arm64: Refactor enter_exception64() [81/89] KVM: arm64: Inject SIGSEGV on illegal accesses [82/89] KVM: arm64: Support TLB invalidation in guest context [83/89] KVM: arm64: Avoid BBM when changing only s/w bits in Stage-2 PTE [84/89] KVM: arm64: Extend memory sharing to allow guest-to-host transitions [85/89] KVM: arm64: Document the KVM/arm64-specific calls in hypercalls.rst [86/89] KVM: arm64: Reformat/beautify PTP hypercall documentation [87/89] KVM: arm64: Expose memory sharing hypercalls to protected guests [88/89] KVM: arm64: Introduce KVM_VM_TYPE_ARM_PROTECTED machine type for PVMs [89/89] Documentation: KVM: Add some documentation for Protected KVM on arm64

Commit Message

Will Deacon May 19, 2022, 1:40 p.m. UTC

has_vhe() expands to a compile-time constant when evaluated from the VHE
or nVHE code, alternatively checking a static key when called from
elsewhere in the kernel. On face value, this looks like a case of
premature optimization, but in fact this allows symbol references on
VHE-specific code paths to be dropped from the nVHE object.

Expand the comment in has_vhe() to make this clearer, hopefully
discouraging anybody from simplifying the code.

Cc: David Brazdil <dbrazdil@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/include/asm/virt.h | 3 +++
 1 file changed, 3 insertions(+)

diff mbox series

Patch

diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h
index 3c8af033a997..0e80db4327b6 100644
--- a/arch/arm64/include/asm/virt.h
+++ b/arch/arm64/include/asm/virt.h
@@ -113,6 +113,9 @@  static __always_inline bool has_vhe(void)
 	/*
 	 * Code only run in VHE/NVHE hyp context can assume VHE is present or
 	 * absent. Otherwise fall back to caps.
+	 * This allows the compiler to discard VHE-specific code from the
+	 * nVHE object, reducing the number of external symbol references
+	 * needed to link.
 	 */
 	if (is_vhe_hyp_code())
 		return true;