From b8cc6eb5bded7078f796b2ebf548f79850281eb6 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Wed, 15 Dec 2021 16:12:30 +0000 Subject: [PATCH] KVM: arm64: Expose unshare hypercall to the host Introduce an unshare hypercall which can be used to unmap memory from the hypervisor stage-1 in nVHE protected mode. This will be useful to update the EL2 ownership state of pages during guest teardown, and avoids keeping dangling mappings to unreferenced portions of memory. Signed-off-by: Will Deacon Signed-off-by: Quentin Perret Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20211215161232.1480836-14-qperret@google.com --- arch/arm64/include/asm/kvm_asm.h | 1 + arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 1 + arch/arm64/kvm/hyp/nvhe/hyp-main.c | 8 +++++++ arch/arm64/kvm/hyp/nvhe/mem_protect.c | 33 +++++++++++++++++++++++++++ 4 files changed, 43 insertions(+) diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h index 50d5e4de244c..d5b0386ef765 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -63,6 +63,7 @@ enum __kvm_host_smccc_func { /* Hypercalls available after pKVM finalisation */ __KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp, + __KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_hyp, __KVM_HOST_SMCCC_FUNC___kvm_adjust_pc, __KVM_HOST_SMCCC_FUNC___kvm_vcpu_run, __KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context, diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h index 56445586c755..80e99836eac7 100644 --- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h +++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h @@ -55,6 +55,7 @@ extern const u8 pkvm_hyp_id; int __pkvm_prot_finalize(void); int __pkvm_host_share_hyp(u64 pfn); +int __pkvm_host_unshare_hyp(u64 pfn); bool addr_is_memory(phys_addr_t phys); int host_stage2_idmap_locked(phys_addr_t addr, u64 size, enum kvm_pgtable_prot prot); diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c index b096bf009144..5e2197db0d32 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -147,6 +147,13 @@ static void handle___pkvm_host_share_hyp(struct kvm_cpu_context *host_ctxt) cpu_reg(host_ctxt, 1) = __pkvm_host_share_hyp(pfn); } +static void handle___pkvm_host_unshare_hyp(struct kvm_cpu_context *host_ctxt) +{ + DECLARE_REG(u64, pfn, host_ctxt, 1); + + cpu_reg(host_ctxt, 1) = __pkvm_host_unshare_hyp(pfn); +} + static void handle___pkvm_create_private_mapping(struct kvm_cpu_context *host_ctxt) { DECLARE_REG(phys_addr_t, phys, host_ctxt, 1); @@ -184,6 +191,7 @@ static const hcall_t host_hcall[] = { HANDLE_FUNC(__pkvm_prot_finalize), HANDLE_FUNC(__pkvm_host_share_hyp), + HANDLE_FUNC(__pkvm_host_unshare_hyp), HANDLE_FUNC(__kvm_adjust_pc), HANDLE_FUNC(__kvm_vcpu_run), HANDLE_FUNC(__kvm_flush_vm_context), diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c index 06973a93db00..33c105ddb6b7 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -768,3 +768,36 @@ int __pkvm_host_share_hyp(u64 pfn) return ret; } + +int __pkvm_host_unshare_hyp(u64 pfn) +{ + int ret; + u64 host_addr = hyp_pfn_to_phys(pfn); + u64 hyp_addr = (u64)__hyp_va(host_addr); + struct pkvm_mem_share share = { + .tx = { + .nr_pages = 1, + .initiator = { + .id = PKVM_ID_HOST, + .addr = host_addr, + .host = { + .completer_addr = hyp_addr, + }, + }, + .completer = { + .id = PKVM_ID_HYP, + }, + }, + .completer_prot = PAGE_HYP, + }; + + host_lock_component(); + hyp_lock_component(); + + ret = do_unshare(&share); + + hyp_unlock_component(); + host_unlock_component(); + + return ret; +} -- 2.11.0