From: Alexandru Elisei <alexandru.elisei@arm.com>
To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu
Cc: maz@kernel.org, will@kernel.org
Subject: [RFC PATCH v3 03/16] KVM: arm64: Hide SPE from guests
Date: Tue, 27 Oct 2020 17:26:52 +0000 [thread overview]
Message-ID: <20201027172705.15181-4-alexandru.elisei@arm.com> (raw)
In-Reply-To: <20201027172705.15181-1-alexandru.elisei@arm.com>
When SPE is not implemented, accesses to the SPE registers cause an
undefined exception. KVM advertises the presence of SPE in the
ID_AA64DFR0_EL1 register, but configures MDCR_EL2 to trap accesses to the
registers and injects an undefined exception when that happens.
The architecture doesn't allow trapping access to the PMBIDR_EL1 register,
which means the guest will be able to read it even if SPE is not advertised
in the ID register. However, since it's usually better for a read to
unexpectedly succeed than to cause an exception, let's stop advertising the
presence of SPE to guests to better match how KVM emulates the
architecture.
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
arch/arm64/kvm/sys_regs.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index d9117bc56237..aa776c006a2a 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -244,6 +244,12 @@ static bool access_vm_reg(struct kvm_vcpu *vcpu,
return true;
}
+static unsigned int spe_visibility(const struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *r)
+{
+ return REG_HIDDEN_GUEST | REG_HIDDEN_USER;
+}
+
static bool access_actlr(struct kvm_vcpu *vcpu,
struct sys_reg_params *p,
const struct sys_reg_desc *r)
@@ -1143,6 +1149,8 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu,
val = cpuid_feature_cap_perfmon_field(val,
ID_AA64DFR0_PMUVER_SHIFT,
ID_AA64DFR0_PMUVER_8_1);
+ /* Don't advertise SPE to guests */
+ val &= ~(0xfUL << ID_AA64DFR0_PMSVER_SHIFT);
} else if (id == SYS_ID_DFR0_EL1) {
/* Limit guests to PMUv3 for ARMv8.1 */
val = cpuid_feature_cap_perfmon_field(val,
@@ -1590,6 +1598,17 @@ static const struct sys_reg_desc sys_reg_descs[] = {
{ SYS_DESC(SYS_FAR_EL1), access_vm_reg, reset_unknown, FAR_EL1 },
{ SYS_DESC(SYS_PAR_EL1), NULL, reset_unknown, PAR_EL1 },
+ { SYS_DESC(SYS_PMSCR_EL1), .visibility = spe_visibility },
+ { SYS_DESC(SYS_PMSICR_EL1), .visibility = spe_visibility },
+ { SYS_DESC(SYS_PMSIRR_EL1), .visibility = spe_visibility },
+ { SYS_DESC(SYS_PMSFCR_EL1), .visibility = spe_visibility },
+ { SYS_DESC(SYS_PMSEVFR_EL1), .visibility = spe_visibility },
+ { SYS_DESC(SYS_PMSLATFR_EL1), .visibility = spe_visibility },
+ { SYS_DESC(SYS_PMSIDR_EL1), .visibility = spe_visibility },
+ { SYS_DESC(SYS_PMBLIMITR_EL1), .visibility = spe_visibility },
+ { SYS_DESC(SYS_PMBPTR_EL1), .visibility = spe_visibility },
+ { SYS_DESC(SYS_PMBSR_EL1), .visibility = spe_visibility },
+
{ SYS_DESC(SYS_PMINTENSET_EL1), access_pminten, reset_unknown, PMINTENSET_EL1 },
{ SYS_DESC(SYS_PMINTENCLR_EL1), access_pminten, reset_unknown, PMINTENSET_EL1 },
--
2.29.1
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next prev parent reply other threads:[~2020-10-27 17:26 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-27 17:26 [RFC PATCH v3 00/16] KVM: arm64: Add Statistical Profiling Extension (SPE) support Alexandru Elisei
2020-10-27 17:26 ` [RFC PATCH v3 01/16] KVM: arm64: Initialize VCPU mdcr_el2 before loading it Alexandru Elisei
2020-11-19 16:58 ` James Morse
2020-12-02 14:25 ` Alexandru Elisei
2020-10-27 17:26 ` [RFC PATCH v3 02/16] dt-bindings: ARM SPE: Highlight the need for PPI partitions on heterogeneous systems Alexandru Elisei
2020-10-27 17:26 ` Alexandru Elisei [this message]
2020-10-27 17:26 ` [RFC PATCH v3 04/16] arm64: Introduce CPU SPE feature Alexandru Elisei
2020-11-19 16:58 ` James Morse
2020-12-02 14:29 ` Alexandru Elisei
2020-12-02 17:23 ` Will Deacon
2020-12-03 10:07 ` Alexandru Elisei
2020-10-27 17:26 ` [RFC PATCH v3 05/16] KVM: arm64: Introduce VCPU " Alexandru Elisei
2020-10-27 17:26 ` [RFC PATCH v3 06/16] KVM: arm64: Introduce SPE primitives Alexandru Elisei
2020-11-19 16:58 ` James Morse
2020-12-02 15:13 ` Alexandru Elisei
2020-10-27 17:26 ` [RFC PATCH v3 07/16] KVM: arm64: Define SPE data structure for each VCPU Alexandru Elisei
2020-10-27 17:26 ` [RFC PATCH v3 08/16] KVM: arm64: Add a new VCPU device control group for SPE Alexandru Elisei
2020-11-05 9:58 ` Haibo Xu
2020-12-02 15:20 ` Alexandru Elisei
2020-11-19 16:58 ` James Morse
2020-12-02 16:28 ` Alexandru Elisei
2020-10-27 17:26 ` [RFC PATCH v3 09/16] KVM: arm64: Use separate function for the mapping size in user_mem_abort() Alexandru Elisei
2020-11-05 10:01 ` Haibo Xu
2020-12-02 16:29 ` Alexandru Elisei
2020-10-27 17:26 ` [RFC PATCH v3 10/16] KVM: arm64: Add a new VM device control group for SPE Alexandru Elisei
2020-11-05 10:10 ` Haibo Xu
2020-12-02 16:35 ` Alexandru Elisei
2020-11-19 16:59 ` James Morse
2021-03-23 14:27 ` Alexandru Elisei
2020-10-27 17:27 ` [RFC PATCH v3 11/16] KVM: arm64: Add SPE system registers to VCPU context Alexandru Elisei
2020-10-27 17:27 ` [RFC PATCH v3 12/16] KVM: arm64: VHE: Clear MDCR_EL2.E2PB in vcpu_put() Alexandru Elisei
2020-10-27 17:27 ` [RFC PATCH v3 13/16] KVM: arm64: Switch SPE context on VM entry/exit Alexandru Elisei
2020-10-27 17:27 ` [RFC PATCH v3 14/16] KVM: arm64: Emulate SPE buffer management interrupt Alexandru Elisei
2020-10-27 17:27 ` [RFC PATCH v3 15/16] KVM: arm64: Enable SPE for guests Alexandru Elisei
2020-10-27 17:27 ` [RFC PATCH v3 16/16] Documentation: arm64: Document ARM Neoverse-N1 erratum #1688567 Alexandru Elisei
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