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Message-Id: <20241127100130.1162639-2-james.clark@linaro.org>
Date: Wed, 27 Nov 2024 10:01:18 +0000
From: James Clark <james.clark@...aro.org>
To: maz@...nel.org,
kvmarm@...ts.linux.dev,
oliver.upton@...ux.dev,
suzuki.poulose@....com,
coresight@...ts.linaro.org
Cc: James Clark <james.clark@...aro.org>,
Joey Gouly <joey.gouly@....com>,
Zenghui Yu <yuzenghui@...wei.com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Mike Leach <mike.leach@...aro.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Mark Rutland <mark.rutland@....com>,
Anshuman Khandual <anshuman.khandual@....com>,
Fuad Tabba <tabba@...gle.com>,
James Morse <james.morse@....com>,
Shiqi Liu <shiqiliu@...t.edu.cn>,
Mark Brown <broonie@...nel.org>,
Raghavendra Rao Ananta <rananta@...gle.com>,
linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v8 1/8] KVM: arm64: Get rid of __kvm_get_mdcr_el2() and related warts
From: Oliver Upton <oliver.upton@...ux.dev>
KVM caches MDCR_EL2 on a per-CPU basis in order to preserve the
configuration of MDCR_EL2.HPMN while running a guest. This is a bit
gross, since we're relying on some baked configuration rather than the
hardware definition of implemented counters.
Discover the number of implemented counters by reading PMCR_EL0.N
instead. This works because:
- In VHE the kernel runs at EL2, and N always returns the number of
counters implemented in hardware
- In {n,h}VHE, the EL2 setup code programs MDCR_EL2.HPMN with the EL2
view of PMCR_EL0.N for the host
Lastly, avoid traps under nested virtualization by saving PMCR_EL0.N in
host data.
Signed-off-by: Oliver Upton <oliver.upton@...ux.dev>
Signed-off-by: James Clark <james.clark@...aro.org>
---
arch/arm64/include/asm/kvm_asm.h | 5 +----
arch/arm64/include/asm/kvm_host.h | 7 +++++--
arch/arm64/kvm/arm.c | 2 +-
arch/arm64/kvm/debug.c | 29 +++++++++++------------------
arch/arm64/kvm/hyp/nvhe/debug-sr.c | 5 -----
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 6 ------
arch/arm64/kvm/hyp/vhe/debug-sr.c | 5 -----
7 files changed, 18 insertions(+), 41 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index ca2590344313..063185c202ce 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -53,8 +53,7 @@
enum __kvm_host_smccc_func {
/* Hypercalls available only prior to pKVM finalisation */
/* __KVM_HOST_SMCCC_FUNC___kvm_hyp_init */
- __KVM_HOST_SMCCC_FUNC___kvm_get_mdcr_el2 = __KVM_HOST_SMCCC_FUNC___kvm_hyp_init + 1,
- __KVM_HOST_SMCCC_FUNC___pkvm_init,
+ __KVM_HOST_SMCCC_FUNC___pkvm_init = __KVM_HOST_SMCCC_FUNC___kvm_hyp_init + 1,
__KVM_HOST_SMCCC_FUNC___pkvm_create_private_mapping,
__KVM_HOST_SMCCC_FUNC___pkvm_cpu_set_vector,
__KVM_HOST_SMCCC_FUNC___kvm_enable_ssbs,
@@ -247,8 +246,6 @@ extern void __kvm_adjust_pc(struct kvm_vcpu *vcpu);
extern u64 __vgic_v3_get_gic_config(void);
extern void __vgic_v3_init_lrs(void);
-extern u64 __kvm_get_mdcr_el2(void);
-
#define __KVM_EXTABLE(from, to) \
" .pushsection __kvm_ex_table, \"a\"\n" \
" .align 3\n" \
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index f333b189fb43..ad514434f3fe 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -642,7 +642,7 @@ struct kvm_host_data {
* host_debug_state contains the host registers which are
* saved and restored during world switches.
*/
- struct {
+ struct {
/* {Break,watch}point registers */
struct kvm_guest_debug_arch regs;
/* Statistical profiling extension */
@@ -652,6 +652,9 @@ struct kvm_host_data {
/* Values of trap registers for the host before guest entry. */
u64 mdcr_el2;
} host_debug_state;
+
+ /* Number of programmable event counters (PMCR_EL0.N) for this CPU */
+ unsigned int nr_event_counters;
};
struct kvm_host_psci_config {
@@ -1332,7 +1335,7 @@ static inline bool kvm_system_needs_idmapped_vectors(void)
static inline void kvm_arch_sync_events(struct kvm *kvm) {}
-void kvm_arm_init_debug(void);
+void kvm_init_host_debug_data(void);
void kvm_arm_vcpu_init_debug(struct kvm_vcpu *vcpu);
void kvm_arm_setup_debug(struct kvm_vcpu *vcpu);
void kvm_arm_clear_debug(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index a102c3aebdbc..ab1bf9ccf385 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -2109,6 +2109,7 @@ static void cpu_set_hyp_vector(void)
static void cpu_hyp_init_context(void)
{
kvm_init_host_cpu_context(host_data_ptr(host_ctxt));
+ kvm_init_host_debug_data();
if (!is_kernel_in_hyp_mode())
cpu_init_hyp_mode();
@@ -2117,7 +2118,6 @@ static void cpu_hyp_init_context(void)
static void cpu_hyp_init_features(void)
{
cpu_set_hyp_vector();
- kvm_arm_init_debug();
if (is_kernel_in_hyp_mode())
kvm_timer_init_vhe();
diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c
index ce8886122ed3..0dbabb6e1108 100644
--- a/arch/arm64/kvm/debug.c
+++ b/arch/arm64/kvm/debug.c
@@ -21,8 +21,6 @@
DBG_MDSCR_KDE | \
DBG_MDSCR_MDE)
-static DEFINE_PER_CPU(u64, mdcr_el2);
-
/*
* save/restore_guest_debug_regs
*
@@ -65,21 +63,6 @@ static void restore_guest_debug_regs(struct kvm_vcpu *vcpu)
*vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS;
}
-/**
- * kvm_arm_init_debug - grab what we need for debug
- *
- * Currently the sole task of this function is to retrieve the initial
- * value of mdcr_el2 so we can preserve MDCR_EL2.HPMN which has
- * presumably been set-up by some knowledgeable bootcode.
- *
- * It is called once per-cpu during CPU hyp initialisation.
- */
-
-void kvm_arm_init_debug(void)
-{
- __this_cpu_write(mdcr_el2, kvm_call_hyp_ret(__kvm_get_mdcr_el2));
-}
-
/**
* kvm_arm_setup_mdcr_el2 - configure vcpu mdcr_el2 value
*
@@ -99,7 +82,8 @@ static void kvm_arm_setup_mdcr_el2(struct kvm_vcpu *vcpu)
* This also clears MDCR_EL2_E2PB_MASK and MDCR_EL2_E2TB_MASK
* to disable guest access to the profiling and trace buffers
*/
- vcpu->arch.mdcr_el2 = __this_cpu_read(mdcr_el2) & MDCR_EL2_HPMN_MASK;
+ vcpu->arch.mdcr_el2 = FIELD_PREP(MDCR_EL2_HPMN,
+ *host_data_ptr(nr_event_counters));
vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM |
MDCR_EL2_TPMS |
MDCR_EL2_TTRF |
@@ -343,3 +327,12 @@ void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu)
vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE_SPE);
vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE_TRBE);
}
+
+void kvm_init_host_debug_data(void)
+{
+ u64 dfr0 = read_sysreg(id_aa64dfr0_el1);
+
+ if (cpuid_feature_extract_signed_field(dfr0, ID_AA64DFR0_EL1_PMUVer_SHIFT) > 0)
+ *host_data_ptr(nr_event_counters) = FIELD_GET(ARMV8_PMU_PMCR_N,
+ read_sysreg(pmcr_el0));
+}
diff --git a/arch/arm64/kvm/hyp/nvhe/debug-sr.c b/arch/arm64/kvm/hyp/nvhe/debug-sr.c
index 53efda0235cf..1e2a26d0196e 100644
--- a/arch/arm64/kvm/hyp/nvhe/debug-sr.c
+++ b/arch/arm64/kvm/hyp/nvhe/debug-sr.c
@@ -106,8 +106,3 @@ void __debug_switch_to_host(struct kvm_vcpu *vcpu)
{
__debug_switch_to_host_common(vcpu);
}
-
-u64 __kvm_get_mdcr_el2(void)
-{
- return read_sysreg(mdcr_el2);
-}
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 6aa0b13d86e5..16f5da3a884a 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -264,11 +264,6 @@ static void handle___vgic_v3_init_lrs(struct kvm_cpu_context *host_ctxt)
__vgic_v3_init_lrs();
}
-static void handle___kvm_get_mdcr_el2(struct kvm_cpu_context *host_ctxt)
-{
- cpu_reg(host_ctxt, 1) = __kvm_get_mdcr_el2();
-}
-
static void handle___vgic_v3_save_vmcr_aprs(struct kvm_cpu_context *host_ctxt)
{
DECLARE_REG(struct vgic_v3_cpu_if *, cpu_if, host_ctxt, 1);
@@ -384,7 +379,6 @@ typedef void (*hcall_t)(struct kvm_cpu_context *);
static const hcall_t host_hcall[] = {
/* ___kvm_hyp_init */
- HANDLE_FUNC(__kvm_get_mdcr_el2),
HANDLE_FUNC(__pkvm_init),
HANDLE_FUNC(__pkvm_create_private_mapping),
HANDLE_FUNC(__pkvm_cpu_set_vector),
diff --git a/arch/arm64/kvm/hyp/vhe/debug-sr.c b/arch/arm64/kvm/hyp/vhe/debug-sr.c
index 289689b2682d..0100339b09e0 100644
--- a/arch/arm64/kvm/hyp/vhe/debug-sr.c
+++ b/arch/arm64/kvm/hyp/vhe/debug-sr.c
@@ -19,8 +19,3 @@ void __debug_switch_to_host(struct kvm_vcpu *vcpu)
{
__debug_switch_to_host_common(vcpu);
}
-
-u64 __kvm_get_mdcr_el2(void)
-{
- return read_sysreg(mdcr_el2);
-}
--
2.34.1
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