From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-12.mta1.migadu.com [95.215.58.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2719F403150 for ; Mon, 7 Sep 2026 07:01:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.12 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788764484; cv=none; b=DD+Aaumgffp3PFDDkbFHQrwakS0EumV1/Ec+ib7lCn3PWcBRCSmPdmBcV75V+ImlK4Ly8ls4w63CKDdlmCnkDYVsOKN/9jv11yTaNIWK4CK3LPs/IFeVvi5PuWMvk/fZdYbgKaOra6NSl9xBTDRUXXM3mnWwGNV8wcuGi/HwTD8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788764484; c=relaxed/simple; bh=kbRhFLruLLEiDeGEjd+pflb7ajVQAAsj00DfZkSrZfA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=k/Z6v0zGXQ9WvHzwXsT3PUk+CoyeKTDgo/T0agCAHBSNOleV+8bwqfk5fHDHxNduMVyjWdDFcIikevQfpmoi8mtpTlOGstffhL2kve6Cw8ABLefmze2pF8zJ7tOFIv9QZy7bM7h7+alN/kae/lLc5F2rlNZVTjJxn6OUbA14edI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=Zgdxe3RR; arc=none smtp.client-ip=95.215.58.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="Zgdxe3RR" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=kbRhFLruLLEiDeGEjd+pflb7ajVQAAsj00DfZkSrZfA=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1788764480; v=1; x=1789369280; b=Zgdxe3RRpZms/kntwrjakMvwqeAN9jrsy6LU02RxYoBAu/4TEfrh5CkaUMW7LpC7jY317NUF 34Y4psisntpvxNUiu2CxT7XdpHdTxGc3bFa014UI3SzOyhOT8LXSq94kA1TIWs4DEvICkPb9pbn X0XHrR7mVTI7pVk52vZdX+V8= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 540ff1370b612f45; Mon, 07 Sep 2026 07:01:20 +0000 X-Mizu-Trace-ID: 540ff1370b612f45 X-Migadu-Flow: FLOW_OUT From: Fuad Tabba To: Marc Zyngier , Oliver Upton , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Catalin Marinas , Will Deacon , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Vincent Donnefort , Quentin Perret , Fuad Tabba Subject: [PATCH v2 10/17] KVM: arm64: Prevent host PC adjustments for protected vCPUs Date: Mon, 7 Sep 2026 07:59:55 +0100 Message-Id: <20260907070002.3333525-11-fuad.tabba@linux.dev> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260907070002.3333525-1-fuad.tabba@linux.dev> References: <20260907070002.3333525-1-fuad.tabba@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit __kvm_adjust_pc() lets the host advance a vCPU's PC or inject an exception, which for a protected vCPU would let the host redirect guest execution. Drop the request there: the entry handlers apply the host's PC_UPDATE_REQ on re-entry, where EL2 allows it. For a non-protected vCPU, adjusting the hyp vCPU while PKVM_HOST_STATE_DIRTY is set loses the update at the next flush and the guest re-executes an emulated MMIO access, so the flag selects which copy to adjust. Adjusting the hyp vCPU copies PC_UPDATE_REQ in and back out again. Without the copy back, INCREMENT_PC outlives the adjustment and the next KVM_SET_VCPU_EVENTS trips WARN_ON(INCREMENT_PC) in kvm_pend_exception(). Unloaded, the host copy is host-writable, so pin it and its VM before adjusting. Only commit_pending_events(), under KVM_SET_VCPU_EVENTS, reaches EL2 with no hyp vCPU loaded. KVM_RUN's call always has one. enter_exception64() reads the VM's MTE flag and a host copy's vcpu->kvm is host-written, so __kvm_adjust_pc_vm() takes the VM as a parameter: the pinned host struct kvm when unloaded, the hyp VM otherwise. Suggested-by: Marc Zyngier Signed-off-by: Fuad Tabba --- arch/arm64/include/asm/kvm_asm.h | 1 + arch/arm64/kvm/hyp/exception.c | 27 ++++++++++------- arch/arm64/kvm/hyp/nvhe/hyp-main.c | 47 +++++++++++++++++++++++++++++- 3 files changed, 63 insertions(+), 12 deletions(-) diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h index e5b92ac09e69e..d149afee7b4bd 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -280,6 +280,7 @@ extern int __kvm_at_s12(struct kvm_vcpu *vcpu, u32 op, u64 vaddr); extern int __kvm_vcpu_run(struct kvm_vcpu *vcpu); extern void __kvm_adjust_pc(struct kvm_vcpu *vcpu); +extern void __kvm_adjust_pc_vm(struct kvm_vcpu *vcpu, struct kvm *kvm); extern bool __vgic_v3_get_gic_config(void); extern void __vgic_v3_init_lrs(void); diff --git a/arch/arm64/kvm/hyp/exception.c b/arch/arm64/kvm/hyp/exception.c index 754e2dc1df54a..bf9d8efce9984 100644 --- a/arch/arm64/kvm/hyp/exception.c +++ b/arch/arm64/kvm/hyp/exception.c @@ -66,8 +66,8 @@ static void __vcpu_write_spsr_und(struct kvm_vcpu *vcpu, u64 val) * Here we manipulate the fields in order of the AArch64 SPSR_ELx layout, from * MSB to LSB. */ -static void enter_exception64(struct kvm_vcpu *vcpu, unsigned long target_mode, - enum exception_type type) +static void enter_exception64(struct kvm_vcpu *vcpu, struct kvm *kvm, + unsigned long target_mode, enum exception_type type) { unsigned long sctlr, vbar, old, new, mode; u64 exc_offset; @@ -109,7 +109,7 @@ static void enter_exception64(struct kvm_vcpu *vcpu, unsigned long target_mode, new |= (old & PSR_C_BIT); new |= (old & PSR_V_BIT); - if (kvm_has_mte(kern_hyp_va(vcpu->kvm))) + if (kvm_has_mte(kvm)) new |= PSR_TCO_BIT; new |= (old & PSR_DIT_BIT); @@ -294,7 +294,7 @@ static void enter_exception32(struct kvm_vcpu *vcpu, u32 mode, u32 vect_offset) *vcpu_pc(vcpu) = vect_offset; } -static void kvm_inject_exception(struct kvm_vcpu *vcpu) +static void kvm_inject_exception(struct kvm_vcpu *vcpu, struct kvm *kvm) { if (vcpu_el1_is_32bit(vcpu)) { switch (vcpu_get_flag(vcpu, EXCEPT_MASK)) { @@ -314,23 +314,23 @@ static void kvm_inject_exception(struct kvm_vcpu *vcpu) } else { switch (vcpu_get_flag(vcpu, EXCEPT_MASK)) { case unpack_vcpu_flag(EXCEPT_AA64_EL1_SYNC): - enter_exception64(vcpu, PSR_MODE_EL1h, except_type_sync); + enter_exception64(vcpu, kvm, PSR_MODE_EL1h, except_type_sync); break; case unpack_vcpu_flag(EXCEPT_AA64_EL1_SERR): - enter_exception64(vcpu, PSR_MODE_EL1h, except_type_serror); + enter_exception64(vcpu, kvm, PSR_MODE_EL1h, except_type_serror); break; case unpack_vcpu_flag(EXCEPT_AA64_EL2_SYNC): - enter_exception64(vcpu, PSR_MODE_EL2h, except_type_sync); + enter_exception64(vcpu, kvm, PSR_MODE_EL2h, except_type_sync); break; case unpack_vcpu_flag(EXCEPT_AA64_EL2_IRQ): - enter_exception64(vcpu, PSR_MODE_EL2h, except_type_irq); + enter_exception64(vcpu, kvm, PSR_MODE_EL2h, except_type_irq); break; case unpack_vcpu_flag(EXCEPT_AA64_EL2_SERR): - enter_exception64(vcpu, PSR_MODE_EL2h, except_type_serror); + enter_exception64(vcpu, kvm, PSR_MODE_EL2h, except_type_serror); break; default: @@ -348,10 +348,10 @@ static void kvm_inject_exception(struct kvm_vcpu *vcpu) * Adjust the guest PC (and potentially exception state) depending on * flags provided by the emulation code. */ -void __kvm_adjust_pc(struct kvm_vcpu *vcpu) +void __kvm_adjust_pc_vm(struct kvm_vcpu *vcpu, struct kvm *kvm) { if (vcpu_get_flag(vcpu, PENDING_EXCEPTION)) { - kvm_inject_exception(vcpu); + kvm_inject_exception(vcpu, kvm); vcpu_clear_flag(vcpu, PENDING_EXCEPTION); vcpu_clear_flag(vcpu, EXCEPT_MASK); } else if (vcpu_get_flag(vcpu, INCREMENT_PC)) { @@ -359,3 +359,8 @@ void __kvm_adjust_pc(struct kvm_vcpu *vcpu) vcpu_clear_flag(vcpu, INCREMENT_PC); } } + +void __kvm_adjust_pc(struct kvm_vcpu *vcpu) +{ + __kvm_adjust_pc_vm(vcpu, kern_hyp_va(vcpu->kvm)); +} diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c index 051c2d95e3b7d..1a3f23e90e563 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -640,11 +640,56 @@ static void handle___pkvm_host_mkyoung_guest(struct kvm_cpu_context *host_ctxt) cpu_reg(host_ctxt, 1) = ret; } +static void adjust_pc_loaded(struct pkvm_hyp_vcpu *hyp_vcpu, + struct kvm_vcpu *host_vcpu) +{ + /* + * PKVM_HOST_STATE_DIRTY names the authoritative copy: the host's + * when set, the hyp vCPU's otherwise. Adjust that one. + */ + if (vcpu_get_flag(host_vcpu, PKVM_HOST_STATE_DIRTY)) { + __kvm_adjust_pc_vm(host_vcpu, hyp_vcpu->vcpu.kvm); + return; + } + + /* Reflect the consumed request back, otherwise it stays pending. */ + vcpu_copy_flag(&hyp_vcpu->vcpu, host_vcpu, PC_UPDATE_REQ); + __kvm_adjust_pc(&hyp_vcpu->vcpu); + vcpu_copy_flag(host_vcpu, &hyp_vcpu->vcpu, PC_UPDATE_REQ); +} + +static void adjust_pc_unloaded(struct kvm_vcpu *host_vcpu) +{ + struct kvm *host_kvm; + + if (!is_protected_kvm_enabled()) { + __kvm_adjust_pc(host_vcpu); + return; + } + + /* The host copy is authoritative, used only while pinned. */ + if (hyp_pin_shared_mem(host_vcpu, host_vcpu + 1)) + return; + + host_kvm = kern_hyp_va(READ_ONCE(host_vcpu->kvm)); + if (!hyp_pin_shared_mem(host_kvm, host_kvm + 1)) { + __kvm_adjust_pc_vm(host_vcpu, host_kvm); + hyp_unpin_shared_mem(host_kvm, host_kvm + 1); + } + hyp_unpin_shared_mem(host_vcpu, host_vcpu + 1); +} + static void handle___kvm_adjust_pc(struct kvm_cpu_context *host_ctxt) { DECLARE_REG(struct kvm_vcpu *, vcpu, host_ctxt, 1); + struct pkvm_hyp_vcpu *hyp_vcpu; + struct kvm_vcpu *host_vcpu; - __kvm_adjust_pc(kern_hyp_va(vcpu)); + host_vcpu = __get_host_hyp_vcpus(vcpu, &hyp_vcpu); + if (!hyp_vcpu) + adjust_pc_unloaded(kern_hyp_va(vcpu)); + else if (!pkvm_hyp_vcpu_is_protected(hyp_vcpu)) + adjust_pc_loaded(hyp_vcpu, host_vcpu); } static void handle___kvm_flush_vm_context(struct kvm_cpu_context *host_ctxt) -- 2.39.5