[PATCH v13 22/85] KVM: Use NULL for struct page pointer to indicate mremapped memory
From: Sean Christopherson <seanjc@google.com>
Date: 2024-10-10 18:25:39
Also in:
kvm, kvm-riscv, kvmarm, linux-arm-kernel, linux-mips, linux-riscv, lkml, loongarch
Subsystem:
kernel virtual machine (kvm), the rest · Maintainers:
Paolo Bonzini, Linus Torvalds
Drop yet another unnecessary magic page value from KVM, as there's zero reason to use a poisoned pointer to indicate "no page". If KVM uses a NULL page pointer, the kernel will explode just as quickly as if KVM uses a poisoned pointer. Never mind the fact that such usage would be a blatant and egregious KVM bug. Tested-by: Alex Bennée <redacted> Signed-off-by: Sean Christopherson <seanjc@google.com> --- include/linux/kvm_host.h | 4 ---- virt/kvm/kvm_main.c | 4 ++-- 2 files changed, 2 insertions(+), 6 deletions(-)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index cbc7b9c04c14..e3c01cbbc41a 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h@@ -273,16 +273,12 @@ enum { READING_SHADOW_PAGE_TABLES, }; -#define KVM_UNMAPPED_PAGE ((void *) 0x500 + POISON_POINTER_DELTA) - struct kvm_host_map { /* * Only valid if the 'pfn' is managed by the host kernel (i.e. There is * a 'struct page' for it. When using mem= kernel parameter some memory * can be used as guest memory but they are not managed by host * kernel). - * If 'pfn' is not managed by the host kernel, this field is - * initialized to KVM_UNMAPPED_PAGE. */ struct page *page; void *hva;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index f1c9a781315c..7acb1a8af2e4 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c@@ -3067,7 +3067,7 @@ void kvm_release_pfn(kvm_pfn_t pfn, bool dirty) int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map) { - map->page = KVM_UNMAPPED_PAGE; + map->page = NULL; map->hva = NULL; map->gfn = gfn;
@@ -3093,7 +3093,7 @@ void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty) if (!map->hva) return; - if (map->page != KVM_UNMAPPED_PAGE) + if (map->page) kunmap(map->page); #ifdef CONFIG_HAS_IOMEM else
--
2.47.0.rc1.288.g06298d1525-goog