From 83bb2c1a01d7127d5adc7d69d7aaa3f7072de2b4 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Tue, 16 Nov 2021 10:20:06 +0000 Subject: [PATCH 1/3] KVM: arm64: Save PSTATE early on exit In order to be able to use primitives such as vcpu_mode_is_32bit(), we need to synchronize the guest PSTATE. However, this is currently done deep into the bowels of the world-switch code, and we do have helpers evaluating this much earlier (__vgic_v3_perform_cpuif_access and handle_aarch32_guest, for example). Move the saving of the guest pstate into the early fixups, which cures the first issue. The second one will be addressed separately. Tested-by: Fuad Tabba Reviewed-by: Fuad Tabba Signed-off-by: Marc Zyngier --- arch/arm64/kvm/hyp/include/hyp/switch.h | 6 ++++++ arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 7 ++++++- 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h index 7a0af1d39303..d79fd101615f 100644 --- a/arch/arm64/kvm/hyp/include/hyp/switch.h +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h @@ -429,6 +429,12 @@ static inline bool kvm_hyp_handle_exit(struct kvm_vcpu *vcpu, u64 *exit_code) */ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) { + /* + * Save PSTATE early so that we can evaluate the vcpu mode + * early on. + */ + vcpu->arch.ctxt.regs.pstate = read_sysreg_el2(SYS_SPSR); + if (ARM_EXCEPTION_CODE(*exit_code) != ARM_EXCEPTION_IRQ) vcpu->arch.fault.esr_el2 = read_sysreg_el2(SYS_ESR); diff --git a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h index de7e14c862e6..7ecca8b07851 100644 --- a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h +++ b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h @@ -70,7 +70,12 @@ static inline void __sysreg_save_el1_state(struct kvm_cpu_context *ctxt) static inline void __sysreg_save_el2_return_state(struct kvm_cpu_context *ctxt) { ctxt->regs.pc = read_sysreg_el2(SYS_ELR); - ctxt->regs.pstate = read_sysreg_el2(SYS_SPSR); + /* + * Guest PSTATE gets saved at guest fixup time in all + * cases. We still need to handle the nVHE host side here. + */ + if (!has_vhe() && ctxt->__hyp_running_vcpu) + ctxt->regs.pstate = read_sysreg_el2(SYS_SPSR); if (cpus_have_final_cap(ARM64_HAS_RAS_EXTN)) ctxt_sys_reg(ctxt, DISR_EL1) = read_sysreg_s(SYS_VDISR_EL2); From 7183b2b5ae6b8d77a37069566d77cf2a74060f7e Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Tue, 16 Nov 2021 12:39:35 +0000 Subject: [PATCH 2/3] KVM: arm64: Move pkvm's special 32bit handling into a generic infrastructure Protected KVM is trying to turn AArch32 exceptions into an illegal exception entry. Unfortunately, it does that in a way that is a bit abrupt, and too early for PSTATE to be available. Instead, move it to the fixup code, which is a more reasonable place for it. This will also be useful for the NV code. Reviewed-by: Fuad Tabba Signed-off-by: Marc Zyngier --- arch/arm64/kvm/hyp/include/hyp/switch.h | 8 ++++++++ arch/arm64/kvm/hyp/nvhe/switch.c | 8 +------- arch/arm64/kvm/hyp/vhe/switch.c | 4 ++++ 3 files changed, 13 insertions(+), 7 deletions(-) diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h index d79fd101615f..96c5f3fb7838 100644 --- a/arch/arm64/kvm/hyp/include/hyp/switch.h +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h @@ -403,6 +403,8 @@ typedef bool (*exit_handler_fn)(struct kvm_vcpu *, u64 *); static const exit_handler_fn *kvm_get_exit_handler_array(struct kvm_vcpu *vcpu); +static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code); + /* * Allow the hypervisor to handle the exit with an exit handler if it has one. * @@ -435,6 +437,12 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) */ vcpu->arch.ctxt.regs.pstate = read_sysreg_el2(SYS_SPSR); + /* + * Check whether we want to repaint the state one way or + * another. + */ + early_exit_filter(vcpu, exit_code); + if (ARM_EXCEPTION_CODE(*exit_code) != ARM_EXCEPTION_IRQ) vcpu->arch.fault.esr_el2 = read_sysreg_el2(SYS_ESR); diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c index c0e3fed26d93..d13115a12434 100644 --- a/arch/arm64/kvm/hyp/nvhe/switch.c +++ b/arch/arm64/kvm/hyp/nvhe/switch.c @@ -233,7 +233,7 @@ static const exit_handler_fn *kvm_get_exit_handler_array(struct kvm_vcpu *vcpu) * Returns false if the guest ran in AArch32 when it shouldn't have, and * thus should exit to the host, or true if a the guest run loop can continue. */ -static bool handle_aarch32_guest(struct kvm_vcpu *vcpu, u64 *exit_code) +static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code) { struct kvm *kvm = kern_hyp_va(vcpu->kvm); @@ -248,10 +248,7 @@ static bool handle_aarch32_guest(struct kvm_vcpu *vcpu, u64 *exit_code) vcpu->arch.target = -1; *exit_code &= BIT(ARM_EXIT_WITH_SERROR_BIT); *exit_code |= ARM_EXCEPTION_IL; - return false; } - - return true; } /* Switch to the guest for legacy non-VHE systems */ @@ -316,9 +313,6 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu) /* Jump in the fire! */ exit_code = __guest_enter(vcpu); - if (unlikely(!handle_aarch32_guest(vcpu, &exit_code))) - break; - /* And we're baaack! */ } while (fixup_guest_exit(vcpu, &exit_code)); diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c index 5a2cb5d9bc4b..fbb26b93c347 100644 --- a/arch/arm64/kvm/hyp/vhe/switch.c +++ b/arch/arm64/kvm/hyp/vhe/switch.c @@ -112,6 +112,10 @@ static const exit_handler_fn *kvm_get_exit_handler_array(struct kvm_vcpu *vcpu) return hyp_exit_handlers; } +static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code) +{ +} + /* Switch to the guest for VHE systems running in EL2 */ static int __kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu) { From 1f80d15020d7f130194821feb1432b67648c632d Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Thu, 25 Nov 2021 15:20:14 +0000 Subject: [PATCH 3/3] KVM: arm64: Avoid setting the upper 32 bits of TCR_EL2 and CPTR_EL2 to 1 Having a signed (1 << 31) constant for TCR_EL2_RES1 and CPTR_EL2_TCPAC causes the upper 32-bit to be set to 1 when assigning them to a 64-bit variable. Bit 32 in TCR_EL2 is no longer RES0 in ARMv8.7: with FEAT_LPA2 it changes the meaning of bits 49:48 and 9:8 in the stage 1 EL2 page table entries. As a result of the sign-extension, a non-VHE kernel can no longer boot on a model with ARMv8.7 enabled. CPTR_EL2 still has the top 32 bits RES0 but we should preempt any future problems Make these top bit constants unsigned as per commit df655b75c43f ("arm64: KVM: Avoid setting the upper 32 bits of VTCR_EL2 to 1"). Signed-off-by: Catalin Marinas Reported-by: Chris January Cc: Cc: Will Deacon Cc: Marc Zyngier Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20211125152014.2806582-1-catalin.marinas@arm.com --- arch/arm64/include/asm/kvm_arm.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h index a39fcf318c77..01d47c5886dc 100644 --- a/arch/arm64/include/asm/kvm_arm.h +++ b/arch/arm64/include/asm/kvm_arm.h @@ -91,7 +91,7 @@ #define HCR_HOST_VHE_FLAGS (HCR_RW | HCR_TGE | HCR_E2H) /* TCR_EL2 Registers bits */ -#define TCR_EL2_RES1 ((1 << 31) | (1 << 23)) +#define TCR_EL2_RES1 ((1U << 31) | (1 << 23)) #define TCR_EL2_TBI (1 << 20) #define TCR_EL2_PS_SHIFT 16 #define TCR_EL2_PS_MASK (7 << TCR_EL2_PS_SHIFT) @@ -276,7 +276,7 @@ #define CPTR_EL2_TFP_SHIFT 10 /* Hyp Coprocessor Trap Register */ -#define CPTR_EL2_TCPAC (1 << 31) +#define CPTR_EL2_TCPAC (1U << 31) #define CPTR_EL2_TAM (1 << 30) #define CPTR_EL2_TTA (1 << 20) #define CPTR_EL2_TFP (1 << CPTR_EL2_TFP_SHIFT)