From: Mark Brown <broonie@kernel.org>
To: Marc Zyngier <maz@kernel.org>,
Oliver Upton <oliver.upton@linux.dev>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Jonathan Corbet <corbet@lwn.net>, Shuah Khan <shuah@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org,
Mark Brown <broonie@kernel.org>
Subject: [PATCH RFC v2 01/22] KVM: arm64: Document why we trap SVE access from the host
Date: Fri, 22 Dec 2023 16:21:09 +0000 [thread overview]
Message-ID: <20231222-kvm-arm64-sme-v2-1-da226cb180bb@kernel.org> (raw)
In-Reply-To: <20231222-kvm-arm64-sme-v2-0-da226cb180bb@kernel.org>
When we exit from a SVE guest we leave the SVE configuration in EL2 as it
was for the guest, only switching back to the host configuration on next
use by the host. This is perhaps a little surprising, add comments
explaining what is going on both in the trap handler and when we configure
the traps.
Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/include/asm/kvm_emulate.h | 1 +
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 1 +
2 files changed, 2 insertions(+)
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 78a550537b67..14d6ff2e2a39 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -598,6 +598,7 @@ static __always_inline u64 kvm_get_reset_cptr_el2(struct kvm_vcpu *vcpu)
} else {
val = CPTR_NVHE_EL2_RES1;
+ /* Leave traps enabled, we will restore EL2 lazily */
if (vcpu_has_sve(vcpu) &&
(vcpu->arch.fp_state == FP_STATE_GUEST_OWNED))
val |= CPTR_EL2_TZ;
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 2385fd03ed87..84deed83e580 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -420,6 +420,7 @@ void handle_trap(struct kvm_cpu_context *host_ctxt)
handle_host_smc(host_ctxt);
break;
case ESR_ELx_EC_SVE:
+ /* Handle lazy restore of the host VL */
if (has_hvhe())
sysreg_clear_set(cpacr_el1, 0, (CPACR_EL1_ZEN_EL1EN |
CPACR_EL1_ZEN_EL0EN));
--
2.30.2
WARNING: multiple messages have this Message-ID (diff)
From: Mark Brown <broonie@kernel.org>
To: Marc Zyngier <maz@kernel.org>,
Oliver Upton <oliver.upton@linux.dev>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Jonathan Corbet <corbet@lwn.net>, Shuah Khan <shuah@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org,
Mark Brown <broonie@kernel.org>
Subject: [PATCH RFC v2 01/22] KVM: arm64: Document why we trap SVE access from the host
Date: Fri, 22 Dec 2023 16:21:09 +0000 [thread overview]
Message-ID: <20231222-kvm-arm64-sme-v2-1-da226cb180bb@kernel.org> (raw)
In-Reply-To: <20231222-kvm-arm64-sme-v2-0-da226cb180bb@kernel.org>
When we exit from a SVE guest we leave the SVE configuration in EL2 as it
was for the guest, only switching back to the host configuration on next
use by the host. This is perhaps a little surprising, add comments
explaining what is going on both in the trap handler and when we configure
the traps.
Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/include/asm/kvm_emulate.h | 1 +
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 1 +
2 files changed, 2 insertions(+)
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 78a550537b67..14d6ff2e2a39 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -598,6 +598,7 @@ static __always_inline u64 kvm_get_reset_cptr_el2(struct kvm_vcpu *vcpu)
} else {
val = CPTR_NVHE_EL2_RES1;
+ /* Leave traps enabled, we will restore EL2 lazily */
if (vcpu_has_sve(vcpu) &&
(vcpu->arch.fp_state == FP_STATE_GUEST_OWNED))
val |= CPTR_EL2_TZ;
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 2385fd03ed87..84deed83e580 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -420,6 +420,7 @@ void handle_trap(struct kvm_cpu_context *host_ctxt)
handle_host_smc(host_ctxt);
break;
case ESR_ELx_EC_SVE:
+ /* Handle lazy restore of the host VL */
if (has_hvhe())
sysreg_clear_set(cpacr_el1, 0, (CPACR_EL1_ZEN_EL1EN |
CPACR_EL1_ZEN_EL0EN));
--
2.30.2
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-12-22 16:21 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-22 16:21 [PATCH RFC v2 00/22] KVM: arm64: Implement support for SME in non-protected guests Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` Mark Brown [this message]
2023-12-22 16:21 ` [PATCH RFC v2 01/22] KVM: arm64: Document why we trap SVE access from the host Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 02/22] arm64/fpsimd: Make SVE<->FPSIMD rewriting available to KVM Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 03/22] KVM: arm64: Move SVE state access macros after feature test macros Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 04/22] KVM: arm64: Store vector lengths in an array Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 05/22] KVM: arm64: Document the KVM ABI for SME Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 06/22] KVM: arm64: Make FFR restore optional in __sve_restore_state() Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 07/22] KVM: arm64: Define guest flags for SME Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 08/22] KVM: arm64: Rename SVE finalization constants to be more general Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 09/22] KVM: arm64: Basic SME system register descriptions Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 10/22] KVM: arm64: Add support for TPIDR2_EL0 Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 11/22] KVM: arm64: Make SMPRI_EL1 RES0 for SME guests Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 12/22] KVM: arm64: Make SVCR a normal system register Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 13/22] KVM: arm64: Context switch SME state for guest Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 14/22] KVM: arm64: Manage and handle SME traps Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 15/22] KVM: arm64: Implement SME vector length configuration Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 16/22] KVM: arm64: Rename sve_state_reg_region Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 17/22] KVM: arm64: Support userspace access to streaming mode SVE registers Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 18/22] KVM: arm64: Expose ZA to userspace Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 19/22] KVM: arm64: Provide userspace access to ZT0 Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 20/22] KVM: arm64: Support SME version configuration via ID registers Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 21/22] KVM: arm64: Provide userspace ABI for enabling SME Mark Brown
2023-12-22 16:21 ` Mark Brown
2023-12-22 16:21 ` [PATCH RFC v2 22/22] KVM: arm64: selftests: Add SME system registers to get-reg-list Mark Brown
2023-12-22 16:21 ` Mark Brown
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