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From: Andrew Scull <ascull@google.com>
To: kvmarm@lists.cs.columbia.edu
Cc: maz@kernel.org, kernel-team@android.com
Subject: [PATCH 32/37] KVM: arm64: nVHE: Unify sysreg state restoration paths
Date: Wed, 15 Jul 2020 19:44:33 +0100
Message-ID: <20200715184438.1390996-33-ascull@google.com> (raw)
In-Reply-To: <20200715184438.1390996-1-ascull@google.com>

These sets of state are moved together as nVHE's speculative AT
workaround depends on their correct interaction. As a consequence of
this change, the workaround is much simpler as both the host and the
guests now share the same code path.

Signed-off-by: Andrew Scull <ascull@google.com>
---
 arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 48 ++++-------
 arch/arm64/kvm/hyp/nvhe/switch.c           | 96 +++++++++-------------
 2 files changed, 54 insertions(+), 90 deletions(-)

diff --git a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
index 0c24c922bae8..cffe7dd3df41 100644
--- a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
+++ b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
@@ -75,25 +75,6 @@ static inline void __sysreg_restore_el1_state(struct kvm_cpu_context *ctxt)
 {
 	write_sysreg(ctxt_sys_reg(ctxt, MPIDR_EL1),	vmpidr_el2);
 	write_sysreg(ctxt_sys_reg(ctxt, CSSELR_EL1),	csselr_el1);
-
-	if (has_vhe() ||
-	    !cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT)) {
-		write_sysreg_el1(ctxt_sys_reg(ctxt, SCTLR_EL1),	SYS_SCTLR);
-		write_sysreg_el1(ctxt_sys_reg(ctxt, TCR_EL1),	SYS_TCR);
-	} else	if (!ctxt->is_host) {
-		/*
-		 * Must only be done for guest registers, hence the context
-		 * test. Pairs with nVHE's __activate_traps().
-		 */
-		write_sysreg_el1((ctxt_sys_reg(ctxt, TCR_EL1) |
-				  TCR_EPD1_MASK | TCR_EPD0_MASK),
-				 SYS_TCR);
-		isb();
-		write_sysreg_el1(ctxt->sys_regs[SCTLR_EL1] | SCTLR_ELx_M,
-				 SYS_SCTLR);
-		isb();
-	}
-
 	write_sysreg_el1(ctxt_sys_reg(ctxt, CPACR_EL1),	SYS_CPACR);
 	write_sysreg_el1(ctxt_sys_reg(ctxt, TTBR0_EL1),	SYS_TTBR0);
 	write_sysreg_el1(ctxt_sys_reg(ctxt, TTBR1_EL1),	SYS_TTBR1);
@@ -109,23 +90,24 @@ static inline void __sysreg_restore_el1_state(struct kvm_cpu_context *ctxt)
 	write_sysreg(ctxt_sys_reg(ctxt, PAR_EL1),	par_el1);
 	write_sysreg(ctxt_sys_reg(ctxt, TPIDR_EL1),	tpidr_el1);
 
-	if (!has_vhe() &&
-	    cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT) &&
-	    ctxt->is_host) {
+	if (!has_vhe()) {
 		/*
-		 * Must only be done for host registers, hence the context
-		 * test. Pairs with nVHE's __deactivate_traps().
+		 * For CPUs that are affected by the speculative AT errata,
+		 * ensure the vcpu's stage 1 and stage 2 translations have been
+		 * configured before before updating TCR_EL1 and SCTLR_EL1 to
+		 * potentially allow any speculative walks to occur. The stage
+		 * 2 will have already been configured by the nVHE switching
+		 * code before calling this function.
 		 */
-		isb();
-		/*
-		 * At this stage, and thanks to the above isb(), S2 is
-		 * deconfigured and disabled. We can now restore the host's
-		 * S1 configuration: SCTLR, and only then TCR.
-		 */
-		write_sysreg_el1(ctxt_sys_reg(ctxt, SCTLR_EL1),	SYS_SCTLR);
-		isb();
-		write_sysreg_el1(ctxt_sys_reg(ctxt, TCR_EL1),	SYS_TCR);
+		asm(ALTERNATIVE("nop", "isb", ARM64_WORKAROUND_SPECULATIVE_AT));
+	}
+
+	write_sysreg_el1(ctxt_sys_reg(ctxt, SCTLR_EL1),	SYS_SCTLR);
+	if (!has_vhe()) {
+		/* Ensure S1 MMU state is restored before allowing S1 walks. */
+		asm(ALTERNATIVE("nop", "isb", ARM64_WORKAROUND_SPECULATIVE_AT));
 	}
+	write_sysreg_el1(ctxt_sys_reg(ctxt, TCR_EL1),	SYS_TCR);
 
 	write_sysreg(ctxt_sys_reg(ctxt, SP_EL1),	sp_el1);
 	write_sysreg_el1(ctxt_sys_reg(ctxt, ELR_EL1),	SYS_ELR);
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 25c64392356b..c87b0a709d35 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -43,43 +43,12 @@ static void __activate_traps(struct kvm_vcpu *vcpu)
 	}
 
 	write_sysreg(val, cptr_el2);
-
-	if (cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT)) {
-		struct kvm_cpu_context *ctxt = &vcpu->arch.ctxt;
-
-		isb();
-		/*
-		 * At this stage, and thanks to the above isb(), S2 is
-		 * configured and enabled. We can now restore the guest's S1
-		 * configuration: SCTLR, and only then TCR.
-		 */
-		write_sysreg_el1(ctxt_sys_reg(ctxt, SCTLR_EL1),	SYS_SCTLR);
-		isb();
-		write_sysreg_el1(ctxt_sys_reg(ctxt, TCR_EL1),	SYS_TCR);
-	}
 }
 
 static void __deactivate_traps(struct kvm_vcpu *host_vcpu, struct kvm_vcpu *vcpu)
 {
 	___deactivate_traps(vcpu);
 
-	if (cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT)) {
-		u64 val;
-
-		/*
-		 * Set the TCR and SCTLR registers in the exact opposite
-		 * sequence as __activate_traps (first prevent walks,
-		 * then force the MMU on). A generous sprinkling of isb()
-		 * ensure that things happen in this exact order.
-		 */
-		val = read_sysreg_el1(SYS_TCR);
-		write_sysreg_el1(val | TCR_EPD1_MASK | TCR_EPD0_MASK, SYS_TCR);
-		isb();
-		val = read_sysreg_el1(SYS_SCTLR);
-		write_sysreg_el1(val | SCTLR_ELx_M, SYS_SCTLR);
-		isb();
-	}
-
 	__deactivate_traps_common();
 
 	write_sysreg(host_vcpu->arch.mdcr_el2, mdcr_el2);
@@ -87,9 +56,12 @@ static void __deactivate_traps(struct kvm_vcpu *host_vcpu, struct kvm_vcpu *vcpu
 	write_sysreg(CPTR_EL2_DEFAULT, cptr_el2);
 }
 
-static void __deactivate_vm(struct kvm_vcpu *vcpu)
+static void __restore_stage2(struct kvm_vcpu *vcpu)
 {
-	write_sysreg(0, vttbr_el2);
+	if (vcpu->arch.hcr_el2 & HCR_VM)
+		__activate_vm(kern_hyp_va(vcpu->arch.hw_mmu));
+	else
+		write_sysreg(0, vttbr_el2);
 }
 
 /* Save VGICv3 state on non-VHE systems */
@@ -147,8 +119,6 @@ static void __pmu_switch_to_host(void)
 static void __kvm_vcpu_switch_to_guest(struct kvm_vcpu *host_vcpu,
 				       struct kvm_vcpu *vcpu)
 {
-	struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt;
-
 	/*
 	 * Having IRQs masked via PMR when entering the guest means the GIC
 	 * will not signal the CPU of interrupts of lower priority, and the
@@ -162,35 +132,14 @@ static void __kvm_vcpu_switch_to_guest(struct kvm_vcpu *host_vcpu,
 
 	__pmu_switch_to_guest();
 
-	/*
-	 * We must restore the 32-bit state before the sysregs, thanks
-	 * to erratum #852523 (Cortex-A57) or #853709 (Cortex-A72).
-	 *
-	 * Also, and in order to be able to deal with erratum #1319537 (A57)
-	 * and #1319367 (A72), we must ensure that all VM-related sysreg are
-	 * restored before we enable S2 translation.
-	 */
-	__sysreg32_restore_state(vcpu);
-	__sysreg_restore_state_nvhe(guest_ctxt);
-
-	__activate_vm(kern_hyp_va(vcpu->arch.hw_mmu));
-	__activate_traps(vcpu);
-
 	__timer_enable_traps(vcpu);
 }
 
 static void __kvm_vcpu_switch_to_host(struct kvm_vcpu *host_vcpu,
 				      struct kvm_vcpu *vcpu)
 {
-	struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt;
-
 	__timer_disable_traps(vcpu);
 
-	__deactivate_traps(host_vcpu, vcpu);
-	__deactivate_vm(vcpu);
-
-	__sysreg_restore_state_nvhe(&host_vcpu->arch.ctxt);
-
 	__pmu_switch_to_host();
 
 	/* Returning to host will clear PSR.I, remask PMR if needed */
@@ -228,6 +177,39 @@ static void __vcpu_restore_state(struct kvm_vcpu *vcpu, bool restore_debug)
 	else
 		__kvm_vcpu_switch_to_guest(running_vcpu, vcpu);
 
+	if (cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT)) {
+		u64 val;
+
+		/*
+		 * Set the TCR and SCTLR registers to prevent any stage 1 or 2
+		 * page table walks or TLB allocations. A generous sprinkling
+		 * of isb() ensure that things happen in this exact order.
+		 */
+		val = read_sysreg_el1(SYS_TCR);
+		write_sysreg_el1(val | TCR_EPD1_MASK | TCR_EPD0_MASK, SYS_TCR);
+		isb();
+		val = read_sysreg_el1(SYS_SCTLR);
+		write_sysreg_el1(val | SCTLR_ELx_M, SYS_SCTLR);
+		isb();
+	}
+
+	/*
+	 * We must restore the 32-bit state before the sysregs, thanks to
+	 * erratum #852523 (Cortex-A57) or #853709 (Cortex-A72).
+	 *
+	 * Also, and in order to deal with the speculative AT errata, we must
+	 * ensure the S2 translation is restored before allowing page table
+	 * walks and TLB allocations when the sysregs are restored.
+	 */
+	__restore_stage2(vcpu);
+	__sysreg32_restore_state(vcpu);
+	__sysreg_restore_state_nvhe(&vcpu->arch.ctxt);
+
+	if (vcpu->arch.ctxt.is_host)
+		__deactivate_traps(vcpu, running_vcpu);
+	else
+		__activate_traps(vcpu);
+
 	__hyp_vgic_restore_state(vcpu);
 
 	/*
@@ -300,7 +282,7 @@ void __noreturn hyp_panic(void)
 	if (vcpu != host_vcpu) {
 		__timer_disable_traps(vcpu);
 		__deactivate_traps(host_vcpu, vcpu);
-		__deactivate_vm(vcpu);
+		__restore_stage2(host_vcpu);
 		__sysreg_restore_state_nvhe(&host_vcpu->arch.ctxt);
 	}
 
-- 
2.27.0.389.gc38d7665816-goog

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  parent reply index

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-15 18:44 [PATCH 00/37] Transform the host into a vCPU Andrew Scull
2020-07-15 18:44 ` [PATCH 01/37] smccc: Make constants available to assembly Andrew Scull
2020-07-15 18:44 ` [PATCH 02/37] KVM: arm64: Move clearing of vcpu debug dirty bit Andrew Scull
2020-07-15 18:44 ` [PATCH 03/37] KVM: arm64: Track running vCPU outside of the CPU context Andrew Scull
2020-07-15 18:44 ` [PATCH 04/37] KVM: arm64: nVHE: Pass pointers consistently to hyp-init Andrew Scull
2020-07-15 18:44 ` [PATCH 05/37] KVM: arm64: nVHE: Break out of the hyp-init idmap Andrew Scull
2020-07-15 18:44 ` [PATCH 06/37] KVM: arm64: Only check pending interrupts if it would trap Andrew Scull
2020-07-17 16:21   ` Marc Zyngier
2020-07-15 18:44 ` [PATCH 07/37] KVM: arm64: Separate SError detection from VAXorcism Andrew Scull
2020-07-18  9:00   ` Marc Zyngier
2020-07-20 14:13     ` Andrew Scull
2020-07-20 14:56       ` Marc Zyngier
2020-07-23  0:59         ` FW: " Renters Cancellation Requests
2020-07-20 15:40   ` Andrew Scull
2020-07-20 15:57     ` Marc Zyngier
2020-07-15 18:44 ` [PATCH 08/37] KVM: arm64: nVHE: Introduce a hyp run loop for the host Andrew Scull
2020-07-15 18:44 ` [PATCH 09/37] smccc: Cast arguments to unsigned long Andrew Scull
2020-07-15 18:44 ` [PATCH 10/37] KVM: arm64: nVHE: Migrate hyp interface to SMCCC Andrew Scull
2020-07-15 18:44 ` [PATCH 11/37] KVM: arm64: nVHE: Migrate hyp-init " Andrew Scull
2020-07-15 18:44 ` [PATCH 12/37] KVM: arm64: nVHE: Fix pointers during SMCCC convertion Andrew Scull
2020-07-15 18:44 ` [PATCH 13/37] KVM: arm64: Rename workaround 2 helpers Andrew Scull
2020-07-15 18:44 ` [PATCH 14/37] KVM: arm64: nVHE: Use __kvm_vcpu_run for the host vcpu Andrew Scull
2020-07-15 18:44 ` [PATCH 15/37] KVM: arm64: Share some context save and restore macros Andrew Scull
2020-07-15 18:44 ` [PATCH 16/37] KVM: arm64: nVHE: Handle stub HVCs in the host loop Andrew Scull
2020-07-15 18:44 ` [PATCH 17/37] KVM: arm64: nVHE: Store host sysregs in host vcpu Andrew Scull
2020-07-15 18:44 ` [PATCH 18/37] KVM: arm64: nVHE: Access pmu_events directly in kvm_host_data Andrew Scull
2020-07-15 18:44 ` [PATCH 19/37] KVM: arm64: nVHE: Drop host_ctxt argument for context switching Andrew Scull
2020-07-15 18:44 ` [PATCH 20/37] KVM: arm64: nVHE: Use host vcpu context for host debug state Andrew Scull
2020-07-15 18:44 ` [PATCH 21/37] KVM: arm64: Move host debug state from vcpu to percpu Andrew Scull
2020-07-15 18:44 ` [PATCH 22/37] KVM: arm64: nVHE: Store host's mdcr_el2 and hcr_el2 in its vcpu Andrew Scull
2020-07-15 18:44 ` [PATCH 23/37] KVM: arm64: Skip __hyp_panic and go direct to hyp_panic Andrew Scull
2020-07-15 18:44 ` [PATCH 24/37] KVM: arm64: Break apart kvm_host_data Andrew Scull
2020-07-15 18:44 ` [PATCH 25/37] KVM: arm64: nVHE: Unify sysreg state saving paths Andrew Scull
2020-07-15 18:44 ` [PATCH 26/37] KVM: arm64: nVHE: Unify 32-bit sysreg " Andrew Scull
2020-07-15 18:44 ` [PATCH 27/37] KVM: arm64: nVHE: Unify vgic save and restore Andrew Scull
2020-07-15 18:44 ` [PATCH 28/37] KVM: arm64: nVHE: Unify fpexc32 saving paths Andrew Scull
2020-07-15 18:44 ` [PATCH 29/37] KVM: arm64: nVHE: Separate the save and restore of debug state Andrew Scull
2020-07-15 18:44 ` [PATCH 30/37] KVM: arm64: nVHE: Remove MMU assumption in speculative AT workaround Andrew Scull
2020-07-15 18:44 ` [PATCH 31/37] KVM: arm64: Move speculative AT ISBs into context Andrew Scull
2020-07-15 18:44 ` Andrew Scull [this message]
2020-07-15 18:44 ` [PATCH 33/37] KVM: arm64: Remove __activate_vm wrapper Andrew Scull
2020-07-15 18:44 ` [PATCH 34/37] KVM: arm64: nVHE: Unify timer restore paths Andrew Scull
2020-07-15 18:44 ` [PATCH 35/37] KVM: arm64: nVHE: Unify PMU event restoration paths Andrew Scull
2020-07-15 18:44 ` [PATCH 36/37] KVM: arm64: nVHE: Unify GIC PMR " Andrew Scull
2020-07-15 18:44 ` [PATCH 37/37] KVM: arm64: Separate save and restore of vcpu trap state Andrew Scull

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