* [PATCH 6.6 0/8] KVM: arm64: Backport of SVE fixes to v6.6
@ 2025-03-21 0:16 Mark Brown
2025-03-21 0:16 ` [PATCH 6.6 1/8] KVM: arm64: Calculate cptr_el2 traps on activating traps Mark Brown
` (7 more replies)
0 siblings, 8 replies; 17+ messages in thread
From: Mark Brown @ 2025-03-21 0:16 UTC (permalink / raw)
To: Greg Kroah-Hartman, Marc Zyngier, Oliver Upton, James Morse,
Suzuki K Poulose, Catalin Marinas, Will Deacon
Cc: linux-arm-kernel, kvmarm, linux-kernel, stable, Mark Brown,
Fuad Tabba, James Clark, Mark Rutland, Eric Auger, Wilco Dijkstra,
Eric Auger, Florian Weimer, Jeremy Linton, Paolo Bonzini
This series backports some recent fixes for SVE/KVM interactions from
Mark Rutland to v6.6.
Signed-off-by: Mark Brown <broonie@kernel.org>
---
Fuad Tabba (1):
KVM: arm64: Calculate cptr_el2 traps on activating traps
Mark Rutland (7):
KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state
KVM: arm64: Remove host FPSIMD saving for non-protected KVM
KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN
KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN
KVM: arm64: Refactor exit handlers
KVM: arm64: Mark some header functions as inline
KVM: arm64: Eagerly switch ZCR_EL{1,2}
arch/arm64/include/asm/kvm_host.h | 7 +--
arch/arm64/include/asm/kvm_hyp.h | 1 +
arch/arm64/kernel/fpsimd.c | 25 --------
arch/arm64/kvm/arm.c | 1 -
arch/arm64/kvm/fpsimd.c | 89 +++++----------------------
arch/arm64/kvm/hyp/entry.S | 5 ++
arch/arm64/kvm/hyp/include/hyp/switch.h | 106 +++++++++++++++++++++-----------
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 15 +----
arch/arm64/kvm/hyp/nvhe/pkvm.c | 29 +--------
arch/arm64/kvm/hyp/nvhe/switch.c | 106 ++++++++++++++++++++++----------
arch/arm64/kvm/hyp/vhe/switch.c | 13 ++--
arch/arm64/kvm/reset.c | 3 +
12 files changed, 182 insertions(+), 218 deletions(-)
---
base-commit: 594a1dd5138a6bbaa1697e5648cce23d2520eba9
change-id: 20250227-stable-sve-6-6-e795d85262b9
Best regards,
--
Mark Brown <broonie@kernel.org>
^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH 6.6 1/8] KVM: arm64: Calculate cptr_el2 traps on activating traps
2025-03-21 0:16 [PATCH 6.6 0/8] KVM: arm64: Backport of SVE fixes to v6.6 Mark Brown
@ 2025-03-21 0:16 ` Mark Brown
2025-03-25 11:28 ` Patch "KVM: arm64: Calculate cptr_el2 traps on activating traps" has been added to the 6.6-stable tree gregkh
2025-03-21 0:16 ` [PATCH 6.6 2/8] KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state Mark Brown
` (6 subsequent siblings)
7 siblings, 1 reply; 17+ messages in thread
From: Mark Brown @ 2025-03-21 0:16 UTC (permalink / raw)
To: Greg Kroah-Hartman, Marc Zyngier, Oliver Upton, James Morse,
Suzuki K Poulose, Catalin Marinas, Will Deacon
Cc: linux-arm-kernel, kvmarm, linux-kernel, stable, Mark Brown,
Fuad Tabba, James Clark
From: Fuad Tabba <tabba@google.com>
[ Upstream commit 2fd5b4b0e7b440602455b79977bfa64dea101e6c ]
Similar to VHE, calculate the value of cptr_el2 from scratch on
activate traps. This removes the need to store cptr_el2 in every
vcpu structure. Moreover, some traps, such as whether the guest
owns the fp registers, need to be set on every vcpu run.
Reported-by: James Clark <james.clark@linaro.org>
Fixes: 5294afdbf45a ("KVM: arm64: Exclude FP ownership from kvm_vcpu_arch")
Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://lore.kernel.org/r/20241216105057.579031-13-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/include/asm/kvm_host.h | 1 -
arch/arm64/kvm/arm.c | 1 -
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 2 --
arch/arm64/kvm/hyp/nvhe/pkvm.c | 27 --------------------
arch/arm64/kvm/hyp/nvhe/switch.c | 52 +++++++++++++++++++++++---------------
5 files changed, 32 insertions(+), 51 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index b84ed3ad91a9eba3a30a6081371f2ec98963de06..6a165ec5d3b74ece3e98e7bf45f3ea94cc30e6ec 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -486,7 +486,6 @@ struct kvm_vcpu_arch {
/* Values of trap registers for the guest. */
u64 hcr_el2;
u64 mdcr_el2;
- u64 cptr_el2;
/* Values of trap registers for the host before guest entry. */
u64 mdcr_el2_host;
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index ffdc2c4d07ee83dbeb78b76d93f700f53af35be6..9818cde948ca9c7028220322aea4ff3706542c93 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1309,7 +1309,6 @@ static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu,
}
vcpu_reset_hcr(vcpu);
- vcpu->arch.cptr_el2 = kvm_get_reset_cptr_el2(vcpu);
/*
* Handle the "start in power-off" case.
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 2385fd03ed87c6c0450a1c2dbe830e95ce235ecc..67cc07283e642ab07e1c98c5745e2c6a2dd4f36e 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -36,7 +36,6 @@ static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
hyp_vcpu->vcpu.arch.hcr_el2 = host_vcpu->arch.hcr_el2;
hyp_vcpu->vcpu.arch.mdcr_el2 = host_vcpu->arch.mdcr_el2;
- hyp_vcpu->vcpu.arch.cptr_el2 = host_vcpu->arch.cptr_el2;
hyp_vcpu->vcpu.arch.iflags = host_vcpu->arch.iflags;
hyp_vcpu->vcpu.arch.fp_state = host_vcpu->arch.fp_state;
@@ -59,7 +58,6 @@ static void sync_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
host_vcpu->arch.ctxt = hyp_vcpu->vcpu.arch.ctxt;
host_vcpu->arch.hcr_el2 = hyp_vcpu->vcpu.arch.hcr_el2;
- host_vcpu->arch.cptr_el2 = hyp_vcpu->vcpu.arch.cptr_el2;
host_vcpu->arch.fault = hyp_vcpu->vcpu.arch.fault;
diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
index 8033ef353a5da406dba355ab73854dfa39e93c27..9e7612343ad66d3dc13b8ee858a4e61e917901c9 100644
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
@@ -26,8 +26,6 @@ static void pvm_init_traps_aa64pfr0(struct kvm_vcpu *vcpu)
const u64 feature_ids = pvm_read_id_reg(vcpu, SYS_ID_AA64PFR0_EL1);
u64 hcr_set = HCR_RW;
u64 hcr_clear = 0;
- u64 cptr_set = 0;
- u64 cptr_clear = 0;
/* Protected KVM does not support AArch32 guests. */
BUILD_BUG_ON(FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_EL0),
@@ -57,21 +55,10 @@ static void pvm_init_traps_aa64pfr0(struct kvm_vcpu *vcpu)
/* Trap AMU */
if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_AMU), feature_ids)) {
hcr_clear |= HCR_AMVOFFEN;
- cptr_set |= CPTR_EL2_TAM;
- }
-
- /* Trap SVE */
- if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_SVE), feature_ids)) {
- if (has_hvhe())
- cptr_clear |= CPACR_EL1_ZEN_EL0EN | CPACR_EL1_ZEN_EL1EN;
- else
- cptr_set |= CPTR_EL2_TZ;
}
vcpu->arch.hcr_el2 |= hcr_set;
vcpu->arch.hcr_el2 &= ~hcr_clear;
- vcpu->arch.cptr_el2 |= cptr_set;
- vcpu->arch.cptr_el2 &= ~cptr_clear;
}
/*
@@ -101,7 +88,6 @@ static void pvm_init_traps_aa64dfr0(struct kvm_vcpu *vcpu)
const u64 feature_ids = pvm_read_id_reg(vcpu, SYS_ID_AA64DFR0_EL1);
u64 mdcr_set = 0;
u64 mdcr_clear = 0;
- u64 cptr_set = 0;
/* Trap/constrain PMU */
if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer), feature_ids)) {
@@ -128,17 +114,8 @@ static void pvm_init_traps_aa64dfr0(struct kvm_vcpu *vcpu)
if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_TraceFilt), feature_ids))
mdcr_set |= MDCR_EL2_TTRF;
- /* Trap Trace */
- if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_TraceVer), feature_ids)) {
- if (has_hvhe())
- cptr_set |= CPACR_EL1_TTA;
- else
- cptr_set |= CPTR_EL2_TTA;
- }
-
vcpu->arch.mdcr_el2 |= mdcr_set;
vcpu->arch.mdcr_el2 &= ~mdcr_clear;
- vcpu->arch.cptr_el2 |= cptr_set;
}
/*
@@ -189,10 +166,6 @@ static void pvm_init_trap_regs(struct kvm_vcpu *vcpu)
/* Clear res0 and set res1 bits to trap potential new features. */
vcpu->arch.hcr_el2 &= ~(HCR_RES0);
vcpu->arch.mdcr_el2 &= ~(MDCR_EL2_RES0);
- if (!has_hvhe()) {
- vcpu->arch.cptr_el2 |= CPTR_NVHE_EL2_RES1;
- vcpu->arch.cptr_el2 &= ~(CPTR_NVHE_EL2_RES0);
- }
}
/*
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index c353a06ee7e6d624b41997021379b7b4cf77453d..1026be1964d9664b8b6de19e048aba91ee6463b0 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -36,34 +36,46 @@ DEFINE_PER_CPU(unsigned long, kvm_hyp_vector);
extern void kvm_nvhe_prepare_backtrace(unsigned long fp, unsigned long pc);
-static void __activate_traps(struct kvm_vcpu *vcpu)
+static void __activate_cptr_traps(struct kvm_vcpu *vcpu)
{
- u64 val;
+ u64 val = CPTR_EL2_TAM; /* Same bit irrespective of E2H */
- ___activate_traps(vcpu);
- __activate_traps_common(vcpu);
+ if (has_hvhe()) {
+ val |= CPACR_ELx_TTA;
- val = vcpu->arch.cptr_el2;
- val |= CPTR_EL2_TAM; /* Same bit irrespective of E2H */
- val |= has_hvhe() ? CPACR_EL1_TTA : CPTR_EL2_TTA;
- if (cpus_have_final_cap(ARM64_SME)) {
- if (has_hvhe())
- val &= ~(CPACR_EL1_SMEN_EL1EN | CPACR_EL1_SMEN_EL0EN);
- else
- val |= CPTR_EL2_TSM;
- }
+ if (guest_owns_fp_regs(vcpu)) {
+ val |= CPACR_ELx_FPEN;
+ if (vcpu_has_sve(vcpu))
+ val |= CPACR_ELx_ZEN;
+ }
+ } else {
+ val |= CPTR_EL2_TTA | CPTR_NVHE_EL2_RES1;
- if (!guest_owns_fp_regs(vcpu)) {
- if (has_hvhe())
- val &= ~(CPACR_EL1_FPEN_EL0EN | CPACR_EL1_FPEN_EL1EN |
- CPACR_EL1_ZEN_EL0EN | CPACR_EL1_ZEN_EL1EN);
- else
- val |= CPTR_EL2_TFP | CPTR_EL2_TZ;
+ /*
+ * Always trap SME since it's not supported in KVM.
+ * TSM is RES1 if SME isn't implemented.
+ */
+ val |= CPTR_EL2_TSM;
- __activate_traps_fpsimd32(vcpu);
+ if (!vcpu_has_sve(vcpu) || !guest_owns_fp_regs(vcpu))
+ val |= CPTR_EL2_TZ;
+
+ if (!guest_owns_fp_regs(vcpu))
+ val |= CPTR_EL2_TFP;
}
+ if (!guest_owns_fp_regs(vcpu))
+ __activate_traps_fpsimd32(vcpu);
+
kvm_write_cptr_el2(val);
+}
+
+static void __activate_traps(struct kvm_vcpu *vcpu)
+{
+ ___activate_traps(vcpu);
+ __activate_traps_common(vcpu);
+ __activate_cptr_traps(vcpu);
+
write_sysreg(__this_cpu_read(kvm_hyp_vector), vbar_el2);
if (cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT)) {
--
2.39.5
^ permalink raw reply related [flat|nested] 17+ messages in thread
* [PATCH 6.6 2/8] KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state
2025-03-21 0:16 [PATCH 6.6 0/8] KVM: arm64: Backport of SVE fixes to v6.6 Mark Brown
2025-03-21 0:16 ` [PATCH 6.6 1/8] KVM: arm64: Calculate cptr_el2 traps on activating traps Mark Brown
@ 2025-03-21 0:16 ` Mark Brown
2025-03-25 11:28 ` Patch "KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state" has been added to the 6.6-stable tree gregkh
2025-03-21 0:16 ` [PATCH 6.6 3/8] KVM: arm64: Remove host FPSIMD saving for non-protected KVM Mark Brown
` (5 subsequent siblings)
7 siblings, 1 reply; 17+ messages in thread
From: Mark Brown @ 2025-03-21 0:16 UTC (permalink / raw)
To: Greg Kroah-Hartman, Marc Zyngier, Oliver Upton, James Morse,
Suzuki K Poulose, Catalin Marinas, Will Deacon
Cc: linux-arm-kernel, kvmarm, linux-kernel, stable, Mark Brown,
Mark Rutland, Eric Auger, Wilco Dijkstra, Eric Auger,
Florian Weimer, Fuad Tabba, Jeremy Linton, Paolo Bonzini
From: Mark Rutland <mark.rutland@arm.com>
[ Upstream commit fbc7e61195e23f744814e78524b73b59faa54ab4 ]
There are several problems with the way hyp code lazily saves the host's
FPSIMD/SVE state, including:
* Host SVE being discarded unexpectedly due to inconsistent
configuration of TIF_SVE and CPACR_ELx.ZEN. This has been seen to
result in QEMU crashes where SVE is used by memmove(), as reported by
Eric Auger:
https://issues.redhat.com/browse/RHEL-68997
* Host SVE state is discarded *after* modification by ptrace, which was an
unintentional ptrace ABI change introduced with lazy discarding of SVE state.
* The host FPMR value can be discarded when running a non-protected VM,
where FPMR support is not exposed to a VM, and that VM uses
FPSIMD/SVE. In these cases the hyp code does not save the host's FPMR
before unbinding the host's FPSIMD/SVE/SME state, leaving a stale
value in memory.
Avoid these by eagerly saving and "flushing" the host's FPSIMD/SVE/SME
state when loading a vCPU such that KVM does not need to save any of the
host's FPSIMD/SVE/SME state. For clarity, fpsimd_kvm_prepare() is
removed and the necessary call to fpsimd_save_and_flush_cpu_state() is
placed in kvm_arch_vcpu_load_fp(). As 'fpsimd_state' and 'fpmr_ptr'
should not be used, they are set to NULL; all uses of these will be
removed in subsequent patches.
Historical problems go back at least as far as v5.17, e.g. erroneous
assumptions about TIF_SVE being clear in commit:
8383741ab2e773a9 ("KVM: arm64: Get rid of host SVE tracking/saving")
... and so this eager save+flush probably needs to be backported to ALL
stable trees.
Fixes: 93ae6b01bafee8fa ("KVM: arm64: Discard any SVE state when entering KVM guests")
Fixes: 8c845e2731041f0f ("arm64/sve: Leave SVE enabled on syscall if we don't context switch")
Fixes: ef3be86021c3bdf3 ("KVM: arm64: Add save/restore support for FPMR")
Reported-by: Eric Auger <eauger@redhat.com>
Reported-by: Wilco Dijkstra <wilco.dijkstra@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Tested-by: Eric Auger <eric.auger@redhat.com>
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Jeremy Linton <jeremy.linton@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-2-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
[ Mark: Handle vcpu/host flag conflict ]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/kernel/fpsimd.c | 25 -------------------------
arch/arm64/kvm/fpsimd.c | 31 ++++++++-----------------------
2 files changed, 8 insertions(+), 48 deletions(-)
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 0137d987631e089c935560eccbc678a258580232..bd4f6c6ee0f318e1f60d40755c0f4915edb415b8 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1707,31 +1707,6 @@ void fpsimd_signal_preserve_current_state(void)
sve_to_fpsimd(current);
}
-/*
- * Called by KVM when entering the guest.
- */
-void fpsimd_kvm_prepare(void)
-{
- if (!system_supports_sve())
- return;
-
- /*
- * KVM does not save host SVE state since we can only enter
- * the guest from a syscall so the ABI means that only the
- * non-saved SVE state needs to be saved. If we have left
- * SVE enabled for performance reasons then update the task
- * state to be FPSIMD only.
- */
- get_cpu_fpsimd_context();
-
- if (test_and_clear_thread_flag(TIF_SVE)) {
- sve_to_fpsimd(current);
- current->thread.fp_type = FP_STATE_FPSIMD;
- }
-
- put_cpu_fpsimd_context();
-}
-
/*
* Associate current's FPSIMD context with this cpu
* The caller must have ownership of the cpu FPSIMD context before calling
diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index 8c1d0d4853df48abf4d089bbde153bcee8d0e6d0..8b55de502c8c220e15e3a6b782d5012b9349b612 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -79,14 +79,16 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
if (!system_supports_fpsimd())
return;
- fpsimd_kvm_prepare();
-
/*
- * We will check TIF_FOREIGN_FPSTATE just before entering the
- * guest in kvm_arch_vcpu_ctxflush_fp() and override this to
- * FP_STATE_FREE if the flag set.
+ * Ensure that any host FPSIMD/SVE/SME state is saved and unbound such
+ * that the host kernel is responsible for restoring this state upon
+ * return to userspace, and the hyp code doesn't need to save anything.
+ *
+ * When the host may use SME, fpsimd_save_and_flush_cpu_state() ensures
+ * that PSTATE.{SM,ZA} == {0,0}.
*/
- vcpu->arch.fp_state = FP_STATE_HOST_OWNED;
+ fpsimd_save_and_flush_cpu_state();
+ vcpu->arch.fp_state = FP_STATE_FREE;
vcpu_clear_flag(vcpu, HOST_SVE_ENABLED);
if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN)
@@ -96,23 +98,6 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
vcpu_clear_flag(vcpu, HOST_SME_ENABLED);
if (read_sysreg(cpacr_el1) & CPACR_EL1_SMEN_EL0EN)
vcpu_set_flag(vcpu, HOST_SME_ENABLED);
-
- /*
- * If PSTATE.SM is enabled then save any pending FP
- * state and disable PSTATE.SM. If we leave PSTATE.SM
- * enabled and the guest does not enable SME via
- * CPACR_EL1.SMEN then operations that should be valid
- * may generate SME traps from EL1 to EL1 which we
- * can't intercept and which would confuse the guest.
- *
- * Do the same for PSTATE.ZA in the case where there
- * is state in the registers which has not already
- * been saved, this is very unlikely to happen.
- */
- if (read_sysreg_s(SYS_SVCR) & (SVCR_SM_MASK | SVCR_ZA_MASK)) {
- vcpu->arch.fp_state = FP_STATE_FREE;
- fpsimd_save_and_flush_cpu_state();
- }
}
}
--
2.39.5
^ permalink raw reply related [flat|nested] 17+ messages in thread
* [PATCH 6.6 3/8] KVM: arm64: Remove host FPSIMD saving for non-protected KVM
2025-03-21 0:16 [PATCH 6.6 0/8] KVM: arm64: Backport of SVE fixes to v6.6 Mark Brown
2025-03-21 0:16 ` [PATCH 6.6 1/8] KVM: arm64: Calculate cptr_el2 traps on activating traps Mark Brown
2025-03-21 0:16 ` [PATCH 6.6 2/8] KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state Mark Brown
@ 2025-03-21 0:16 ` Mark Brown
2025-03-25 11:28 ` Patch "KVM: arm64: Remove host FPSIMD saving for non-protected KVM" has been added to the 6.6-stable tree gregkh
2025-03-21 0:16 ` [PATCH 6.6 4/8] KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN Mark Brown
` (4 subsequent siblings)
7 siblings, 1 reply; 17+ messages in thread
From: Mark Brown @ 2025-03-21 0:16 UTC (permalink / raw)
To: Greg Kroah-Hartman, Marc Zyngier, Oliver Upton, James Morse,
Suzuki K Poulose, Catalin Marinas, Will Deacon
Cc: linux-arm-kernel, kvmarm, linux-kernel, stable, Mark Brown,
Mark Rutland, Fuad Tabba
From: Mark Rutland <mark.rutland@arm.com>
[ Upstream commit 8eca7f6d5100b6997df4f532090bc3f7e0203bef ]
Now that the host eagerly saves its own FPSIMD/SVE/SME state,
non-protected KVM never needs to save the host FPSIMD/SVE/SME state,
and the code to do this is never used. Protected KVM still needs to
save/restore the host FPSIMD/SVE state to avoid leaking guest state to
the host (and to avoid revealing to the host whether the guest used
FPSIMD/SVE/SME), and that code needs to be retained.
Remove the unused code and data structures.
To avoid the need for a stub copy of kvm_hyp_save_fpsimd_host() in the
VHE hyp code, the nVHE/hVHE version is moved into the shared switch
header, where it is only invoked when KVM is in protected mode.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-3-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/include/asm/kvm_host.h | 1 -
arch/arm64/kvm/fpsimd.c | 2 --
arch/arm64/kvm/hyp/include/hyp/switch.h | 4 ----
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 1 -
4 files changed, 8 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 6a165ec5d3b74ece3e98e7bf45f3ea94cc30e6ec..3891963d42e00c8f999886dc5d7322bbacbc6c7f 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -535,7 +535,6 @@ struct kvm_vcpu_arch {
struct kvm_guest_debug_arch vcpu_debug_state;
struct kvm_guest_debug_arch external_debug_state;
- struct user_fpsimd_state *host_fpsimd_state; /* hyp VA */
struct task_struct *parent_task;
struct {
diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index 8b55de502c8c220e15e3a6b782d5012b9349b612..7c36d2a7aa3196056f76acfe8f9c41763ed67d9d 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -49,8 +49,6 @@ int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu)
if (ret)
return ret;
- vcpu->arch.host_fpsimd_state = kern_hyp_va(fpsimd);
-
/*
* We need to keep current's task_struct pinned until its data has been
* unshared with the hypervisor to make sure it is not re-used by the
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 9cfe6bd1dbe459cb3588bccd94359369a546947e..1cdc8d161e7dd3aeeb6b03170e239b0c1ace7790 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -321,10 +321,6 @@ static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
}
isb();
- /* Write out the host state if it's in the registers */
- if (vcpu->arch.fp_state == FP_STATE_HOST_OWNED)
- __fpsimd_save_state(vcpu->arch.host_fpsimd_state);
-
/* Restore the guest state */
if (sve_guest)
__hyp_sve_restore_guest(vcpu);
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 67cc07283e642ab07e1c98c5745e2c6a2dd4f36e..8390173f7f5b38e01c04ae6563853df11a1c3df2 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -41,7 +41,6 @@ static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
hyp_vcpu->vcpu.arch.fp_state = host_vcpu->arch.fp_state;
hyp_vcpu->vcpu.arch.debug_ptr = kern_hyp_va(host_vcpu->arch.debug_ptr);
- hyp_vcpu->vcpu.arch.host_fpsimd_state = host_vcpu->arch.host_fpsimd_state;
hyp_vcpu->vcpu.arch.vsesr_el2 = host_vcpu->arch.vsesr_el2;
--
2.39.5
^ permalink raw reply related [flat|nested] 17+ messages in thread
* [PATCH 6.6 4/8] KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN
2025-03-21 0:16 [PATCH 6.6 0/8] KVM: arm64: Backport of SVE fixes to v6.6 Mark Brown
` (2 preceding siblings ...)
2025-03-21 0:16 ` [PATCH 6.6 3/8] KVM: arm64: Remove host FPSIMD saving for non-protected KVM Mark Brown
@ 2025-03-21 0:16 ` Mark Brown
2025-03-25 11:28 ` Patch "KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN" has been added to the 6.6-stable tree gregkh
2025-03-21 0:16 ` [PATCH 6.6 5/8] KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN Mark Brown
` (3 subsequent siblings)
7 siblings, 1 reply; 17+ messages in thread
From: Mark Brown @ 2025-03-21 0:16 UTC (permalink / raw)
To: Greg Kroah-Hartman, Marc Zyngier, Oliver Upton, James Morse,
Suzuki K Poulose, Catalin Marinas, Will Deacon
Cc: linux-arm-kernel, kvmarm, linux-kernel, stable, Mark Brown,
Mark Rutland, Fuad Tabba
From: Mark Rutland <mark.rutland@arm.com>
[ Upstream commit 459f059be702056d91537b99a129994aa6ccdd35 ]
When KVM is in VHE mode, the host kernel tries to save and restore the
configuration of CPACR_EL1.ZEN (i.e. CPTR_EL2.ZEN when HCR_EL2.E2H=1)
across kvm_arch_vcpu_load_fp() and kvm_arch_vcpu_put_fp(), since the
configuration may be clobbered by hyp when running a vCPU. This logic is
currently redundant.
The VHE hyp code unconditionally configures CPTR_EL2.ZEN to 0b01 when
returning to the host, permitting host kernel usage of SVE.
Now that the host eagerly saves and unbinds its own FPSIMD/SVE/SME
state, there's no need to save/restore the state of the EL0 SVE trap.
The kernel can safely save/restore state without trapping, as described
above, and will restore userspace state (including trap controls) before
returning to userspace.
Remove the redundant logic.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-4-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
[Rework for refactoring of where the flags are stored -- broonie]
Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/include/asm/kvm_host.h | 2 --
arch/arm64/kvm/fpsimd.c | 16 ----------------
2 files changed, 18 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 3891963d42e00c8f999886dc5d7322bbacbc6c7f..9c1056d6f6859522dcee4b8c4e4804a7abac93d5 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -717,8 +717,6 @@ struct kvm_vcpu_arch {
/* vcpu running in HYP context */
#define VCPU_HYP_CONTEXT __vcpu_single_flag(iflags, BIT(7))
-/* SVE enabled for host EL0 */
-#define HOST_SVE_ENABLED __vcpu_single_flag(sflags, BIT(0))
/* SME enabled for EL0 */
#define HOST_SME_ENABLED __vcpu_single_flag(sflags, BIT(1))
/* Physical CPU not in supported_cpus */
diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index 7c36d2a7aa3196056f76acfe8f9c41763ed67d9d..f1fe7abbcb83393e7c3402405bb7b1fdbf6024ff 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -88,10 +88,6 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
fpsimd_save_and_flush_cpu_state();
vcpu->arch.fp_state = FP_STATE_FREE;
- vcpu_clear_flag(vcpu, HOST_SVE_ENABLED);
- if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN)
- vcpu_set_flag(vcpu, HOST_SVE_ENABLED);
-
if (system_supports_sme()) {
vcpu_clear_flag(vcpu, HOST_SME_ENABLED);
if (read_sysreg(cpacr_el1) & CPACR_EL1_SMEN_EL0EN)
@@ -189,18 +185,6 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
}
fpsimd_save_and_flush_cpu_state();
- } else if (has_vhe() && system_supports_sve()) {
- /*
- * The FPSIMD/SVE state in the CPU has not been touched, and we
- * have SVE (and VHE): CPACR_EL1 (alias CPTR_EL2) has been
- * reset by kvm_reset_cptr_el2() in the Hyp code, disabling SVE
- * for EL0. To avoid spurious traps, restore the trap state
- * seen by kvm_arch_vcpu_load_fp():
- */
- if (vcpu_get_flag(vcpu, HOST_SVE_ENABLED))
- sysreg_clear_set(CPACR_EL1, 0, CPACR_EL1_ZEN_EL0EN);
- else
- sysreg_clear_set(CPACR_EL1, CPACR_EL1_ZEN_EL0EN, 0);
}
local_irq_restore(flags);
--
2.39.5
^ permalink raw reply related [flat|nested] 17+ messages in thread
* [PATCH 6.6 5/8] KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN
2025-03-21 0:16 [PATCH 6.6 0/8] KVM: arm64: Backport of SVE fixes to v6.6 Mark Brown
` (3 preceding siblings ...)
2025-03-21 0:16 ` [PATCH 6.6 4/8] KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN Mark Brown
@ 2025-03-21 0:16 ` Mark Brown
2025-03-25 11:28 ` Patch "KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN" has been added to the 6.6-stable tree gregkh
2025-03-21 0:16 ` [PATCH 6.6 6/8] KVM: arm64: Refactor exit handlers Mark Brown
` (2 subsequent siblings)
7 siblings, 1 reply; 17+ messages in thread
From: Mark Brown @ 2025-03-21 0:16 UTC (permalink / raw)
To: Greg Kroah-Hartman, Marc Zyngier, Oliver Upton, James Morse,
Suzuki K Poulose, Catalin Marinas, Will Deacon
Cc: linux-arm-kernel, kvmarm, linux-kernel, stable, Mark Brown,
Mark Rutland, Fuad Tabba
From: Mark Rutland <mark.rutland@arm.com>
[ Upstream commit 407a99c4654e8ea65393f412c421a55cac539f5b ]
When KVM is in VHE mode, the host kernel tries to save and restore the
configuration of CPACR_EL1.SMEN (i.e. CPTR_EL2.SMEN when HCR_EL2.E2H=1)
across kvm_arch_vcpu_load_fp() and kvm_arch_vcpu_put_fp(), since the
configuration may be clobbered by hyp when running a vCPU. This logic
has historically been broken, and is currently redundant.
This logic was originally introduced in commit:
861262ab86270206 ("KVM: arm64: Handle SME host state when running guests")
At the time, the VHE hyp code would reset CPTR_EL2.SMEN to 0b00 when
returning to the host, trapping host access to SME state. Unfortunately,
this was unsafe as the host could take a softirq before calling
kvm_arch_vcpu_put_fp(), and if a softirq handler were to use kernel mode
NEON the resulting attempt to save the live FPSIMD/SVE/SME state would
result in a fatal trap.
That issue was limited to VHE mode. For nVHE/hVHE modes, KVM always
saved/restored the host kernel's CPACR_EL1 value, and configured
CPTR_EL2.TSM to 0b0, ensuring that host usage of SME would not be
trapped.
The issue above was incidentally fixed by commit:
375110ab51dec5dc ("KVM: arm64: Fix resetting SME trap values on reset for (h)VHE")
That commit changed the VHE hyp code to configure CPTR_EL2.SMEN to 0b01
when returning to the host, permitting host kernel usage of SME,
avoiding the issue described above. At the time, this was not identified
as a fix for commit 861262ab86270206.
Now that the host eagerly saves and unbinds its own FPSIMD/SVE/SME
state, there's no need to save/restore the state of the EL0 SME trap.
The kernel can safely save/restore state without trapping, as described
above, and will restore userspace state (including trap controls) before
returning to userspace.
Remove the redundant logic.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-5-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
[Update for rework of flags storage -- broonie]
Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/include/asm/kvm_host.h | 2 --
arch/arm64/kvm/fpsimd.c | 23 -----------------------
2 files changed, 25 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 9c1056d6f6859522dcee4b8c4e4804a7abac93d5..27c53b603d693d1cfe8d81f94a59d3afb665be8e 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -717,8 +717,6 @@ struct kvm_vcpu_arch {
/* vcpu running in HYP context */
#define VCPU_HYP_CONTEXT __vcpu_single_flag(iflags, BIT(7))
-/* SME enabled for EL0 */
-#define HOST_SME_ENABLED __vcpu_single_flag(sflags, BIT(1))
/* Physical CPU not in supported_cpus */
#define ON_UNSUPPORTED_CPU __vcpu_single_flag(sflags, BIT(2))
/* WFIT instruction trapped */
diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index f1fe7abbcb83393e7c3402405bb7b1fdbf6024ff..0492a1fc718130934f8bada836fe42bea6db7abb 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -87,12 +87,6 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
*/
fpsimd_save_and_flush_cpu_state();
vcpu->arch.fp_state = FP_STATE_FREE;
-
- if (system_supports_sme()) {
- vcpu_clear_flag(vcpu, HOST_SME_ENABLED);
- if (read_sysreg(cpacr_el1) & CPACR_EL1_SMEN_EL0EN)
- vcpu_set_flag(vcpu, HOST_SME_ENABLED);
- }
}
/*
@@ -157,23 +151,6 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
local_irq_save(flags);
- /*
- * If we have VHE then the Hyp code will reset CPACR_EL1 to
- * the default value and we need to reenable SME.
- */
- if (has_vhe() && system_supports_sme()) {
- /* Also restore EL0 state seen on entry */
- if (vcpu_get_flag(vcpu, HOST_SME_ENABLED))
- sysreg_clear_set(CPACR_EL1, 0,
- CPACR_EL1_SMEN_EL0EN |
- CPACR_EL1_SMEN_EL1EN);
- else
- sysreg_clear_set(CPACR_EL1,
- CPACR_EL1_SMEN_EL0EN,
- CPACR_EL1_SMEN_EL1EN);
- isb();
- }
-
if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED) {
if (vcpu_has_sve(vcpu)) {
__vcpu_sys_reg(vcpu, ZCR_EL1) = read_sysreg_el1(SYS_ZCR);
--
2.39.5
^ permalink raw reply related [flat|nested] 17+ messages in thread
* [PATCH 6.6 6/8] KVM: arm64: Refactor exit handlers
2025-03-21 0:16 [PATCH 6.6 0/8] KVM: arm64: Backport of SVE fixes to v6.6 Mark Brown
` (4 preceding siblings ...)
2025-03-21 0:16 ` [PATCH 6.6 5/8] KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN Mark Brown
@ 2025-03-21 0:16 ` Mark Brown
2025-03-25 11:28 ` Patch "KVM: arm64: Refactor exit handlers" has been added to the 6.6-stable tree gregkh
2025-03-21 0:16 ` [PATCH 6.6 7/8] KVM: arm64: Mark some header functions as inline Mark Brown
2025-03-21 0:16 ` [PATCH 6.6 8/8] KVM: arm64: Eagerly switch ZCR_EL{1,2} Mark Brown
7 siblings, 1 reply; 17+ messages in thread
From: Mark Brown @ 2025-03-21 0:16 UTC (permalink / raw)
To: Greg Kroah-Hartman, Marc Zyngier, Oliver Upton, James Morse,
Suzuki K Poulose, Catalin Marinas, Will Deacon
Cc: linux-arm-kernel, kvmarm, linux-kernel, stable, Mark Brown,
Mark Rutland, Fuad Tabba
From: Mark Rutland <mark.rutland@arm.com>
[ Upstream commit 9b66195063c5a145843547b1d692bd189be85287 ]
The hyp exit handling logic is largely shared between VHE and nVHE/hVHE,
with common logic in arch/arm64/kvm/hyp/include/hyp/switch.h. The code
in the header depends on function definitions provided by
arch/arm64/kvm/hyp/vhe/switch.c and arch/arm64/kvm/hyp/nvhe/switch.c
when they include the header.
This is an unusual header dependency, and prevents the use of
arch/arm64/kvm/hyp/include/hyp/switch.h in other files as this would
result in compiler warnings regarding missing definitions, e.g.
| In file included from arch/arm64/kvm/hyp/nvhe/hyp-main.c:8:
| ./arch/arm64/kvm/hyp/include/hyp/switch.h:733:31: warning: 'kvm_get_exit_handler_array' used but never defined
| 733 | static const exit_handler_fn *kvm_get_exit_handler_array(struct kvm_vcpu *vcpu);
| | ^~~~~~~~~~~~~~~~~~~~~~~~~~
| ./arch/arm64/kvm/hyp/include/hyp/switch.h:735:13: warning: 'early_exit_filter' used but never defined
| 735 | static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code);
| | ^~~~~~~~~~~~~~~~~
Refactor the logic such that the header doesn't depend on anything from
the C files. There should be no functional change as a result of this
patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-7-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/kvm/hyp/include/hyp/switch.h | 30 ++++++------------------------
arch/arm64/kvm/hyp/nvhe/switch.c | 27 +++++++++++++++------------
arch/arm64/kvm/hyp/vhe/switch.c | 9 ++++-----
3 files changed, 25 insertions(+), 41 deletions(-)
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 1cdc8d161e7dd3aeeb6b03170e239b0c1ace7790..db9570affe09d36f2fe4641789a24111303be5a2 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -592,23 +592,16 @@ static bool kvm_hyp_handle_dabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
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.
*
* Returns true if the hypervisor handled the exit, and control should go back
* to the guest, or false if it hasn't.
*/
-static inline bool kvm_hyp_handle_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
+static inline bool kvm_hyp_handle_exit(struct kvm_vcpu *vcpu, u64 *exit_code,
+ const exit_handler_fn *handlers)
{
- const exit_handler_fn *handlers = kvm_get_exit_handler_array(vcpu);
- exit_handler_fn fn;
-
- fn = handlers[kvm_vcpu_trap_get_class(vcpu)];
-
+ exit_handler_fn fn = handlers[kvm_vcpu_trap_get_class(vcpu)];
if (fn)
return fn(vcpu, exit_code);
@@ -638,20 +631,9 @@ static inline void synchronize_vcpu_pstate(struct kvm_vcpu *vcpu, u64 *exit_code
* the guest, false when we should restore the host state and return to the
* main run loop.
*/
-static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
+static inline bool __fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code,
+ const exit_handler_fn *handlers)
{
- /*
- * Save PSTATE early so that we can evaluate the vcpu mode
- * early on.
- */
- synchronize_vcpu_pstate(vcpu, exit_code);
-
- /*
- * 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);
@@ -681,7 +663,7 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
goto exit;
/* Check if there's an exit handler and allow it to handle the exit. */
- if (kvm_hyp_handle_exit(vcpu, exit_code))
+ if (kvm_hyp_handle_exit(vcpu, exit_code, handlers))
goto guest;
exit:
/* Return to the host kernel and handle the exit */
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 1026be1964d9664b8b6de19e048aba91ee6463b0..aa827e2a2b1e5b2c67304221706f406b42ceafb2 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -225,21 +225,22 @@ static const exit_handler_fn *kvm_get_exit_handler_array(struct kvm_vcpu *vcpu)
return hyp_exit_handlers;
}
-/*
- * Some guests (e.g., protected VMs) are not be allowed to run in AArch32.
- * The ARMv8 architecture does not give the hypervisor a mechanism to prevent a
- * guest from dropping to AArch32 EL0 if implemented by the CPU. If the
- * hypervisor spots a guest in such a state ensure it is handled, and don't
- * trust the host to spot or fix it. The check below is based on the one in
- * kvm_arch_vcpu_ioctl_run().
- *
- * 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 void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code)
+static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
{
+ const exit_handler_fn *handlers = kvm_get_exit_handler_array(vcpu);
struct kvm *kvm = kern_hyp_va(vcpu->kvm);
+ synchronize_vcpu_pstate(vcpu, exit_code);
+
+ /*
+ * Some guests (e.g., protected VMs) are not be allowed to run in
+ * AArch32. The ARMv8 architecture does not give the hypervisor a
+ * mechanism to prevent a guest from dropping to AArch32 EL0 if
+ * implemented by the CPU. If the hypervisor spots a guest in such a
+ * state ensure it is handled, and don't trust the host to spot or fix
+ * it. The check below is based on the one in
+ * kvm_arch_vcpu_ioctl_run().
+ */
if (kvm_vm_is_protected(kvm) && vcpu_mode_is_32bit(vcpu)) {
/*
* As we have caught the guest red-handed, decide that it isn't
@@ -252,6 +253,8 @@ static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code)
*exit_code &= BIT(ARM_EXIT_WITH_SERROR_BIT);
*exit_code |= ARM_EXCEPTION_IL;
}
+
+ return __fixup_guest_exit(vcpu, exit_code, handlers);
}
/* Switch to the guest for legacy non-VHE systems */
diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
index 448b17080d3617cbf5d2fceec7e7fa62866760d4..d0c7725879a7b38cea53f1dfb111933e0ad89845 100644
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -172,13 +172,10 @@ static const exit_handler_fn hyp_exit_handlers[] = {
[ESR_ELx_EC_PAC] = kvm_hyp_handle_ptrauth,
};
-static const exit_handler_fn *kvm_get_exit_handler_array(struct kvm_vcpu *vcpu)
+static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
{
- return hyp_exit_handlers;
-}
+ synchronize_vcpu_pstate(vcpu, exit_code);
-static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code)
-{
/*
* If we were in HYP context on entry, adjust the PSTATE view
* so that the usual helpers work correctly.
@@ -198,6 +195,8 @@ static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code)
*vcpu_cpsr(vcpu) &= ~(PSR_MODE_MASK | PSR_MODE32_BIT);
*vcpu_cpsr(vcpu) |= mode;
}
+
+ return __fixup_guest_exit(vcpu, exit_code, hyp_exit_handlers);
}
/* Switch to the guest for VHE systems running in EL2 */
--
2.39.5
^ permalink raw reply related [flat|nested] 17+ messages in thread
* [PATCH 6.6 7/8] KVM: arm64: Mark some header functions as inline
2025-03-21 0:16 [PATCH 6.6 0/8] KVM: arm64: Backport of SVE fixes to v6.6 Mark Brown
` (5 preceding siblings ...)
2025-03-21 0:16 ` [PATCH 6.6 6/8] KVM: arm64: Refactor exit handlers Mark Brown
@ 2025-03-21 0:16 ` Mark Brown
2025-03-25 11:28 ` Patch "KVM: arm64: Mark some header functions as inline" has been added to the 6.6-stable tree gregkh
2025-03-21 0:16 ` [PATCH 6.6 8/8] KVM: arm64: Eagerly switch ZCR_EL{1,2} Mark Brown
7 siblings, 1 reply; 17+ messages in thread
From: Mark Brown @ 2025-03-21 0:16 UTC (permalink / raw)
To: Greg Kroah-Hartman, Marc Zyngier, Oliver Upton, James Morse,
Suzuki K Poulose, Catalin Marinas, Will Deacon
Cc: linux-arm-kernel, kvmarm, linux-kernel, stable, Mark Brown,
Mark Rutland, Fuad Tabba
From: Mark Rutland <mark.rutland@arm.com>
[ Upstream commit f9dd00de1e53a47763dfad601635d18542c3836d ]
The shared hyp switch header has a number of static functions which
might not be used by all files that include the header, and when unused
they will provoke compiler warnings, e.g.
| In file included from arch/arm64/kvm/hyp/nvhe/hyp-main.c:8:
| ./arch/arm64/kvm/hyp/include/hyp/switch.h:703:13: warning: 'kvm_hyp_handle_dabt_low' defined but not used [-Wunused-function]
| 703 | static bool kvm_hyp_handle_dabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
| | ^~~~~~~~~~~~~~~~~~~~~~~
| ./arch/arm64/kvm/hyp/include/hyp/switch.h:682:13: warning: 'kvm_hyp_handle_cp15_32' defined but not used [-Wunused-function]
| 682 | static bool kvm_hyp_handle_cp15_32(struct kvm_vcpu *vcpu, u64 *exit_code)
| | ^~~~~~~~~~~~~~~~~~~~~~
| ./arch/arm64/kvm/hyp/include/hyp/switch.h:662:13: warning: 'kvm_hyp_handle_sysreg' defined but not used [-Wunused-function]
| 662 | static bool kvm_hyp_handle_sysreg(struct kvm_vcpu *vcpu, u64 *exit_code)
| | ^~~~~~~~~~~~~~~~~~~~~
| ./arch/arm64/kvm/hyp/include/hyp/switch.h:458:13: warning: 'kvm_hyp_handle_fpsimd' defined but not used [-Wunused-function]
| 458 | static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
| | ^~~~~~~~~~~~~~~~~~~~~
| ./arch/arm64/kvm/hyp/include/hyp/switch.h:329:13: warning: 'kvm_hyp_handle_mops' defined but not used [-Wunused-function]
| 329 | static bool kvm_hyp_handle_mops(struct kvm_vcpu *vcpu, u64 *exit_code)
| | ^~~~~~~~~~~~~~~~~~~
Mark these functions as 'inline' to suppress this warning. This
shouldn't result in any functional change.
At the same time, avoid the use of __alias() in the header and alias
kvm_hyp_handle_iabt_low() and kvm_hyp_handle_watchpt_low() to
kvm_hyp_handle_memory_fault() using CPP, matching the style in the rest
of the kernel. For consistency, kvm_hyp_handle_memory_fault() is also
marked as 'inline'.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-8-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/kvm/hyp/include/hyp/switch.h | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index db9570affe09d36f2fe4641789a24111303be5a2..77a9f68ca4904a2b39ca59b7ee7cf54b9fe11f66 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -279,7 +279,7 @@ static inline void __hyp_sve_restore_guest(struct kvm_vcpu *vcpu)
* If FP/SIMD is not implemented, handle the trap and inject an undefined
* instruction exception to the guest. Similarly for trapped SVE accesses.
*/
-static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
+static inline bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
{
bool sve_guest;
u8 esr_ec;
@@ -518,7 +518,7 @@ static bool handle_ampere1_tcr(struct kvm_vcpu *vcpu)
return true;
}
-static bool kvm_hyp_handle_sysreg(struct kvm_vcpu *vcpu, u64 *exit_code)
+static inline bool kvm_hyp_handle_sysreg(struct kvm_vcpu *vcpu, u64 *exit_code)
{
if (cpus_have_final_cap(ARM64_WORKAROUND_CAVIUM_TX2_219_TVM) &&
handle_tx2_tvm(vcpu))
@@ -541,7 +541,7 @@ static bool kvm_hyp_handle_sysreg(struct kvm_vcpu *vcpu, u64 *exit_code)
return false;
}
-static bool kvm_hyp_handle_cp15_32(struct kvm_vcpu *vcpu, u64 *exit_code)
+static inline bool kvm_hyp_handle_cp15_32(struct kvm_vcpu *vcpu, u64 *exit_code)
{
if (static_branch_unlikely(&vgic_v3_cpuif_trap) &&
__vgic_v3_perform_cpuif_access(vcpu) == 1)
@@ -550,19 +550,18 @@ static bool kvm_hyp_handle_cp15_32(struct kvm_vcpu *vcpu, u64 *exit_code)
return false;
}
-static bool kvm_hyp_handle_memory_fault(struct kvm_vcpu *vcpu, u64 *exit_code)
+static inline bool kvm_hyp_handle_memory_fault(struct kvm_vcpu *vcpu,
+ u64 *exit_code)
{
if (!__populate_fault_info(vcpu))
return true;
return false;
}
-static bool kvm_hyp_handle_iabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
- __alias(kvm_hyp_handle_memory_fault);
-static bool kvm_hyp_handle_watchpt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
- __alias(kvm_hyp_handle_memory_fault);
+#define kvm_hyp_handle_iabt_low kvm_hyp_handle_memory_fault
+#define kvm_hyp_handle_watchpt_low kvm_hyp_handle_memory_fault
-static bool kvm_hyp_handle_dabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
+static inline bool kvm_hyp_handle_dabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
{
if (kvm_hyp_handle_memory_fault(vcpu, exit_code))
return true;
--
2.39.5
^ permalink raw reply related [flat|nested] 17+ messages in thread
* [PATCH 6.6 8/8] KVM: arm64: Eagerly switch ZCR_EL{1,2}
2025-03-21 0:16 [PATCH 6.6 0/8] KVM: arm64: Backport of SVE fixes to v6.6 Mark Brown
` (6 preceding siblings ...)
2025-03-21 0:16 ` [PATCH 6.6 7/8] KVM: arm64: Mark some header functions as inline Mark Brown
@ 2025-03-21 0:16 ` Mark Brown
2025-03-25 11:28 ` Patch "KVM: arm64: Eagerly switch ZCR_EL{1,2}" has been added to the 6.6-stable tree gregkh
7 siblings, 1 reply; 17+ messages in thread
From: Mark Brown @ 2025-03-21 0:16 UTC (permalink / raw)
To: Greg Kroah-Hartman, Marc Zyngier, Oliver Upton, James Morse,
Suzuki K Poulose, Catalin Marinas, Will Deacon
Cc: linux-arm-kernel, kvmarm, linux-kernel, stable, Mark Brown,
Mark Rutland, Fuad Tabba
From: Mark Rutland <mark.rutland@arm.com>
[ Upstream commit 59419f10045bc955d2229819c7cf7a8b0b9c5b59 ]
In non-protected KVM modes, while the guest FPSIMD/SVE/SME state is live on the
CPU, the host's active SVE VL may differ from the guest's maximum SVE VL:
* For VHE hosts, when a VM uses NV, ZCR_EL2 contains a value constrained
by the guest hypervisor, which may be less than or equal to that
guest's maximum VL.
Note: in this case the value of ZCR_EL1 is immaterial due to E2H.
* For nVHE/hVHE hosts, ZCR_EL1 contains a value written by the guest,
which may be less than or greater than the guest's maximum VL.
Note: in this case hyp code traps host SVE usage and lazily restores
ZCR_EL2 to the host's maximum VL, which may be greater than the
guest's maximum VL.
This can be the case between exiting a guest and kvm_arch_vcpu_put_fp().
If a softirq is taken during this period and the softirq handler tries
to use kernel-mode NEON, then the kernel will fail to save the guest's
FPSIMD/SVE state, and will pend a SIGKILL for the current thread.
This happens because kvm_arch_vcpu_ctxsync_fp() binds the guest's live
FPSIMD/SVE state with the guest's maximum SVE VL, and
fpsimd_save_user_state() verifies that the live SVE VL is as expected
before attempting to save the register state:
| if (WARN_ON(sve_get_vl() != vl)) {
| force_signal_inject(SIGKILL, SI_KERNEL, 0, 0);
| return;
| }
Fix this and make this a bit easier to reason about by always eagerly
switching ZCR_EL{1,2} at hyp during guest<->host transitions. With this
happening, there's no need to trap host SVE usage, and the nVHE/nVHE
__deactivate_cptr_traps() logic can be simplified to enable host access
to all present FPSIMD/SVE/SME features.
In protected nVHE/hVHE modes, the host's state is always saved/restored
by hyp, and the guest's state is saved prior to exit to the host, so
from the host's PoV the guest never has live FPSIMD/SVE/SME state, and
the host's ZCR_EL1 is never clobbered by hyp.
Fixes: 8c8010d69c132273 ("KVM: arm64: Save/restore SVE state for nVHE")
Fixes: 2e3cf82063a00ea0 ("KVM: arm64: nv: Ensure correct VL is loaded before saving SVE state")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-9-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
[ v6.6 lacks pKVM saving of host SVE state, pull in discovery of maximum
host VL separately -- broonie ]
Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/include/asm/kvm_host.h | 1 +
arch/arm64/include/asm/kvm_hyp.h | 1 +
arch/arm64/kvm/fpsimd.c | 19 ++++++------
arch/arm64/kvm/hyp/entry.S | 5 +++
arch/arm64/kvm/hyp/include/hyp/switch.h | 55 +++++++++++++++++++++++++++++++++
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 12 ++-----
arch/arm64/kvm/hyp/nvhe/pkvm.c | 2 ++
arch/arm64/kvm/hyp/nvhe/switch.c | 33 +++++++++++++++++---
arch/arm64/kvm/hyp/vhe/switch.c | 4 +++
arch/arm64/kvm/reset.c | 3 ++
10 files changed, 113 insertions(+), 22 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 27c53b603d693d1cfe8d81f94a59d3afb665be8e..df73e452d2cc0e5fd815d398a932763a5aa7607a 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -73,6 +73,7 @@ static inline enum kvm_mode kvm_get_mode(void) { return KVM_MODE_NONE; };
#endif
extern unsigned int __ro_after_init kvm_sve_max_vl;
+extern unsigned int __ro_after_init kvm_host_sve_max_vl;
int __init kvm_arm_init_sve(void);
u32 __attribute_const__ kvm_target_cpu(void);
diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
index 66efd67ea7e8d6dd98dc6088a6004fdb646df2a3..51cd106cd840a006264d9a316f2dc6332e8327ad 100644
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -145,5 +145,6 @@ extern u64 kvm_nvhe_sym(id_aa64smfr0_el1_sys_val);
extern unsigned long kvm_nvhe_sym(__icache_flags);
extern unsigned int kvm_nvhe_sym(kvm_arm_vmid_bits);
+extern unsigned int kvm_nvhe_sym(kvm_host_sve_max_vl);
#endif /* __ARM64_KVM_HYP_H__ */
diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index 0492a1fc718130934f8bada836fe42bea6db7abb..e57db49ea468e41e411fd896321c3b1b87a098ec 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -152,15 +152,16 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
local_irq_save(flags);
if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED) {
- if (vcpu_has_sve(vcpu)) {
- __vcpu_sys_reg(vcpu, ZCR_EL1) = read_sysreg_el1(SYS_ZCR);
-
- /* Restore the VL that was saved when bound to the CPU */
- if (!has_vhe())
- sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1,
- SYS_ZCR_EL1);
- }
-
+ /*
+ * Flush (save and invalidate) the fpsimd/sve state so that if
+ * the host tries to use fpsimd/sve, it's not using stale data
+ * from the guest.
+ *
+ * Flushing the state sets the TIF_FOREIGN_FPSTATE bit for the
+ * context unconditionally, in both nVHE and VHE. This allows
+ * the kernel to restore the fpsimd/sve state, including ZCR_EL1
+ * when needed.
+ */
fpsimd_save_and_flush_cpu_state();
}
diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S
index f3aa7738b477d6a83e41db42cc161fc6f9aa6291..f02d5701fc21c685122aa5ba92309f7f4def3ae3 100644
--- a/arch/arm64/kvm/hyp/entry.S
+++ b/arch/arm64/kvm/hyp/entry.S
@@ -44,6 +44,11 @@ alternative_if ARM64_HAS_RAS_EXTN
alternative_else_nop_endif
mrs x1, isr_el1
cbz x1, 1f
+
+ // Ensure that __guest_enter() always provides a context
+ // synchronization event so that callers don't need ISBs for anything
+ // that would usually be synchonized by the ERET.
+ isb
mov x0, #ARM_EXCEPTION_IRQ
ret
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 77a9f68ca4904a2b39ca59b7ee7cf54b9fe11f66..526085401f66387137a0d78d1d520af8b2306e43 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -273,6 +273,61 @@ static inline void __hyp_sve_restore_guest(struct kvm_vcpu *vcpu)
write_sysreg_el1(__vcpu_sys_reg(vcpu, ZCR_EL1), SYS_ZCR);
}
+static inline void fpsimd_lazy_switch_to_guest(struct kvm_vcpu *vcpu)
+{
+ u64 zcr_el1, zcr_el2;
+
+ if (!guest_owns_fp_regs(vcpu))
+ return;
+
+ if (vcpu_has_sve(vcpu)) {
+ zcr_el2 = vcpu_sve_max_vq(vcpu) - 1;
+
+ write_sysreg_el2(zcr_el2, SYS_ZCR);
+
+ zcr_el1 = __vcpu_sys_reg(vcpu, ZCR_EL1);
+ write_sysreg_el1(zcr_el1, SYS_ZCR);
+ }
+}
+
+static inline void fpsimd_lazy_switch_to_host(struct kvm_vcpu *vcpu)
+{
+ u64 zcr_el1, zcr_el2;
+
+ if (!guest_owns_fp_regs(vcpu))
+ return;
+
+ /*
+ * When the guest owns the FP regs, we know that guest+hyp traps for
+ * any FPSIMD/SVE/SME features exposed to the guest have been disabled
+ * by either fpsimd_lazy_switch_to_guest() or kvm_hyp_handle_fpsimd()
+ * prior to __guest_entry(). As __guest_entry() guarantees a context
+ * synchronization event, we don't need an ISB here to avoid taking
+ * traps for anything that was exposed to the guest.
+ */
+ if (vcpu_has_sve(vcpu)) {
+ zcr_el1 = read_sysreg_el1(SYS_ZCR);
+ __vcpu_sys_reg(vcpu, ZCR_EL1) = zcr_el1;
+
+ /*
+ * The guest's state is always saved using the guest's max VL.
+ * Ensure that the host has the guest's max VL active such that
+ * the host can save the guest's state lazily, but don't
+ * artificially restrict the host to the guest's max VL.
+ */
+ if (has_vhe()) {
+ zcr_el2 = vcpu_sve_max_vq(vcpu) - 1;
+ write_sysreg_el2(zcr_el2, SYS_ZCR);
+ } else {
+ zcr_el2 = sve_vq_from_vl(kvm_host_sve_max_vl) - 1;
+ write_sysreg_el2(zcr_el2, SYS_ZCR);
+
+ zcr_el1 = vcpu_sve_max_vq(vcpu) - 1;
+ write_sysreg_el1(zcr_el1, SYS_ZCR);
+ }
+ }
+}
+
/*
* We trap the first access to the FP/SIMD to save the host context and
* restore the guest context lazily.
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 8390173f7f5b38e01c04ae6563853df11a1c3df2..350d1775a5ce880ac23bb7adddbed644e45d0e40 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -5,6 +5,7 @@
*/
#include <hyp/adjust_pc.h>
+#include <hyp/switch.h>
#include <asm/pgtable-types.h>
#include <asm/kvm_asm.h>
@@ -95,7 +96,9 @@ static void handle___kvm_vcpu_run(struct kvm_cpu_context *host_ctxt)
pkvm_put_hyp_vcpu(hyp_vcpu);
} else {
/* The host is fully trusted, run its vCPU directly. */
+ fpsimd_lazy_switch_to_guest(host_vcpu);
ret = __kvm_vcpu_run(host_vcpu);
+ fpsimd_lazy_switch_to_host(host_vcpu);
}
out:
@@ -416,15 +419,6 @@ void handle_trap(struct kvm_cpu_context *host_ctxt)
case ESR_ELx_EC_SMC64:
handle_host_smc(host_ctxt);
break;
- case ESR_ELx_EC_SVE:
- if (has_hvhe())
- sysreg_clear_set(cpacr_el1, 0, (CPACR_EL1_ZEN_EL1EN |
- CPACR_EL1_ZEN_EL0EN));
- else
- sysreg_clear_set(cptr_el2, CPTR_EL2_TZ, 0);
- isb();
- sve_cond_update_zcr_vq(ZCR_ELx_LEN_MASK, SYS_ZCR_EL2);
- break;
case ESR_ELx_EC_IABT_LOW:
case ESR_ELx_EC_DABT_LOW:
handle_host_mem_abort(host_ctxt);
diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
index 9e7612343ad66d3dc13b8ee858a4e61e917901c9..03acc8343c5d1b23ce0ea1fa2fcabaf2a93902c5 100644
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
@@ -18,6 +18,8 @@ unsigned long __icache_flags;
/* Used by kvm_get_vttbr(). */
unsigned int kvm_arm_vmid_bits;
+unsigned int kvm_host_sve_max_vl;
+
/*
* Set trap register values based on features in ID_AA64PFR0.
*/
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index aa827e2a2b1e5b2c67304221706f406b42ceafb2..27ad6933bec003d722d3d66519b6225cd207cad7 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -40,6 +40,9 @@ static void __activate_cptr_traps(struct kvm_vcpu *vcpu)
{
u64 val = CPTR_EL2_TAM; /* Same bit irrespective of E2H */
+ if (!guest_owns_fp_regs(vcpu))
+ __activate_traps_fpsimd32(vcpu);
+
if (has_hvhe()) {
val |= CPACR_ELx_TTA;
@@ -48,6 +51,8 @@ static void __activate_cptr_traps(struct kvm_vcpu *vcpu)
if (vcpu_has_sve(vcpu))
val |= CPACR_ELx_ZEN;
}
+
+ write_sysreg(val, cpacr_el1);
} else {
val |= CPTR_EL2_TTA | CPTR_NVHE_EL2_RES1;
@@ -62,12 +67,32 @@ static void __activate_cptr_traps(struct kvm_vcpu *vcpu)
if (!guest_owns_fp_regs(vcpu))
val |= CPTR_EL2_TFP;
+
+ write_sysreg(val, cptr_el2);
}
+}
- if (!guest_owns_fp_regs(vcpu))
- __activate_traps_fpsimd32(vcpu);
+static void __deactivate_cptr_traps(struct kvm_vcpu *vcpu)
+{
+ if (has_hvhe()) {
+ u64 val = CPACR_ELx_FPEN;
+
+ if (cpus_have_final_cap(ARM64_SVE))
+ val |= CPACR_ELx_ZEN;
+ if (cpus_have_final_cap(ARM64_SME))
+ val |= CPACR_ELx_SMEN;
+
+ write_sysreg(val, cpacr_el1);
+ } else {
+ u64 val = CPTR_NVHE_EL2_RES1;
+
+ if (!cpus_have_final_cap(ARM64_SVE))
+ val |= CPTR_EL2_TZ;
+ if (!cpus_have_final_cap(ARM64_SME))
+ val |= CPTR_EL2_TSM;
- kvm_write_cptr_el2(val);
+ write_sysreg(val, cptr_el2);
+ }
}
static void __activate_traps(struct kvm_vcpu *vcpu)
@@ -120,7 +145,7 @@ static void __deactivate_traps(struct kvm_vcpu *vcpu)
write_sysreg(this_cpu_ptr(&kvm_init_params)->hcr_el2, hcr_el2);
- kvm_reset_cptr_el2(vcpu);
+ __deactivate_cptr_traps(vcpu);
write_sysreg(__kvm_hyp_host_vector, vbar_el2);
}
diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
index d0c7725879a7b38cea53f1dfb111933e0ad89845..31304da0d617313244caff582853965a7a206f72 100644
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -212,6 +212,8 @@ static int __kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
sysreg_save_host_state_vhe(host_ctxt);
+ fpsimd_lazy_switch_to_guest(vcpu);
+
/*
* ARM erratum 1165522 requires us to configure both stage 1 and
* stage 2 translation for the guest context before we clear
@@ -247,6 +249,8 @@ static int __kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
__deactivate_traps(vcpu);
+ fpsimd_lazy_switch_to_host(vcpu);
+
sysreg_restore_host_state_vhe(host_ctxt);
if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED)
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 7a65a35ee4ac4165b4147c724d28b59f8150a0d2..43a53a403f5102c81bba0d928c0f78331f800269 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -46,11 +46,14 @@ static u32 __ro_after_init kvm_ipa_limit;
PSR_AA32_I_BIT | PSR_AA32_F_BIT)
unsigned int __ro_after_init kvm_sve_max_vl;
+unsigned int __ro_after_init kvm_host_sve_max_vl;
int __init kvm_arm_init_sve(void)
{
if (system_supports_sve()) {
kvm_sve_max_vl = sve_max_virtualisable_vl();
+ kvm_host_sve_max_vl = sve_max_vl();
+ kvm_nvhe_sym(kvm_host_sve_max_vl) = kvm_host_sve_max_vl;
/*
* The get_sve_reg()/set_sve_reg() ioctl interface will need
--
2.39.5
^ permalink raw reply related [flat|nested] 17+ messages in thread
* Patch "KVM: arm64: Calculate cptr_el2 traps on activating traps" has been added to the 6.6-stable tree
2025-03-21 0:16 ` [PATCH 6.6 1/8] KVM: arm64: Calculate cptr_el2 traps on activating traps Mark Brown
@ 2025-03-25 11:28 ` gregkh
0 siblings, 0 replies; 17+ messages in thread
From: gregkh @ 2025-03-25 11:28 UTC (permalink / raw)
To: broonie, catalin.marinas, gregkh, james.clark, james.morse,
kvmarm, linux-arm-kernel, maz, oliver.upton, suzuki.poulose,
tabba, will
Cc: stable-commits
This is a note to let you know that I've just added the patch titled
KVM: arm64: Calculate cptr_el2 traps on activating traps
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-arm64-calculate-cptr_el2-traps-on-activating-traps.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
From stable+bounces-125719-greg=kroah.com@vger.kernel.org Thu Mar 20 20:19:30 2025
From: Mark Brown <broonie@kernel.org>
Date: Fri, 21 Mar 2025 00:16:01 +0000
Subject: KVM: arm64: Calculate cptr_el2 traps on activating traps
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 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>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Mark Brown <broonie@kernel.org>, Fuad Tabba <tabba@google.com>, James Clark <james.clark@linaro.org>
Message-ID: <20250321-stable-sve-6-6-v1-1-0b3a6a14ea53@kernel.org>
From: Fuad Tabba <tabba@google.com>
[ Upstream commit 2fd5b4b0e7b440602455b79977bfa64dea101e6c ]
Similar to VHE, calculate the value of cptr_el2 from scratch on
activate traps. This removes the need to store cptr_el2 in every
vcpu structure. Moreover, some traps, such as whether the guest
owns the fp registers, need to be set on every vcpu run.
Reported-by: James Clark <james.clark@linaro.org>
Fixes: 5294afdbf45a ("KVM: arm64: Exclude FP ownership from kvm_vcpu_arch")
Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://lore.kernel.org/r/20241216105057.579031-13-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/include/asm/kvm_host.h | 1
arch/arm64/kvm/arm.c | 1
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 2 -
arch/arm64/kvm/hyp/nvhe/pkvm.c | 27 -------------------
arch/arm64/kvm/hyp/nvhe/switch.c | 52 ++++++++++++++++++++++---------------
5 files changed, 32 insertions(+), 51 deletions(-)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -486,7 +486,6 @@ struct kvm_vcpu_arch {
/* Values of trap registers for the guest. */
u64 hcr_el2;
u64 mdcr_el2;
- u64 cptr_el2;
/* Values of trap registers for the host before guest entry. */
u64 mdcr_el2_host;
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1309,7 +1309,6 @@ static int kvm_arch_vcpu_ioctl_vcpu_init
}
vcpu_reset_hcr(vcpu);
- vcpu->arch.cptr_el2 = kvm_get_reset_cptr_el2(vcpu);
/*
* Handle the "start in power-off" case.
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -36,7 +36,6 @@ static void flush_hyp_vcpu(struct pkvm_h
hyp_vcpu->vcpu.arch.hcr_el2 = host_vcpu->arch.hcr_el2;
hyp_vcpu->vcpu.arch.mdcr_el2 = host_vcpu->arch.mdcr_el2;
- hyp_vcpu->vcpu.arch.cptr_el2 = host_vcpu->arch.cptr_el2;
hyp_vcpu->vcpu.arch.iflags = host_vcpu->arch.iflags;
hyp_vcpu->vcpu.arch.fp_state = host_vcpu->arch.fp_state;
@@ -59,7 +58,6 @@ static void sync_hyp_vcpu(struct pkvm_hy
host_vcpu->arch.ctxt = hyp_vcpu->vcpu.arch.ctxt;
host_vcpu->arch.hcr_el2 = hyp_vcpu->vcpu.arch.hcr_el2;
- host_vcpu->arch.cptr_el2 = hyp_vcpu->vcpu.arch.cptr_el2;
host_vcpu->arch.fault = hyp_vcpu->vcpu.arch.fault;
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
@@ -26,8 +26,6 @@ static void pvm_init_traps_aa64pfr0(stru
const u64 feature_ids = pvm_read_id_reg(vcpu, SYS_ID_AA64PFR0_EL1);
u64 hcr_set = HCR_RW;
u64 hcr_clear = 0;
- u64 cptr_set = 0;
- u64 cptr_clear = 0;
/* Protected KVM does not support AArch32 guests. */
BUILD_BUG_ON(FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_EL0),
@@ -57,21 +55,10 @@ static void pvm_init_traps_aa64pfr0(stru
/* Trap AMU */
if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_AMU), feature_ids)) {
hcr_clear |= HCR_AMVOFFEN;
- cptr_set |= CPTR_EL2_TAM;
- }
-
- /* Trap SVE */
- if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_SVE), feature_ids)) {
- if (has_hvhe())
- cptr_clear |= CPACR_EL1_ZEN_EL0EN | CPACR_EL1_ZEN_EL1EN;
- else
- cptr_set |= CPTR_EL2_TZ;
}
vcpu->arch.hcr_el2 |= hcr_set;
vcpu->arch.hcr_el2 &= ~hcr_clear;
- vcpu->arch.cptr_el2 |= cptr_set;
- vcpu->arch.cptr_el2 &= ~cptr_clear;
}
/*
@@ -101,7 +88,6 @@ static void pvm_init_traps_aa64dfr0(stru
const u64 feature_ids = pvm_read_id_reg(vcpu, SYS_ID_AA64DFR0_EL1);
u64 mdcr_set = 0;
u64 mdcr_clear = 0;
- u64 cptr_set = 0;
/* Trap/constrain PMU */
if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer), feature_ids)) {
@@ -128,17 +114,8 @@ static void pvm_init_traps_aa64dfr0(stru
if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_TraceFilt), feature_ids))
mdcr_set |= MDCR_EL2_TTRF;
- /* Trap Trace */
- if (!FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_TraceVer), feature_ids)) {
- if (has_hvhe())
- cptr_set |= CPACR_EL1_TTA;
- else
- cptr_set |= CPTR_EL2_TTA;
- }
-
vcpu->arch.mdcr_el2 |= mdcr_set;
vcpu->arch.mdcr_el2 &= ~mdcr_clear;
- vcpu->arch.cptr_el2 |= cptr_set;
}
/*
@@ -189,10 +166,6 @@ static void pvm_init_trap_regs(struct kv
/* Clear res0 and set res1 bits to trap potential new features. */
vcpu->arch.hcr_el2 &= ~(HCR_RES0);
vcpu->arch.mdcr_el2 &= ~(MDCR_EL2_RES0);
- if (!has_hvhe()) {
- vcpu->arch.cptr_el2 |= CPTR_NVHE_EL2_RES1;
- vcpu->arch.cptr_el2 &= ~(CPTR_NVHE_EL2_RES0);
- }
}
/*
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -36,34 +36,46 @@ DEFINE_PER_CPU(unsigned long, kvm_hyp_ve
extern void kvm_nvhe_prepare_backtrace(unsigned long fp, unsigned long pc);
-static void __activate_traps(struct kvm_vcpu *vcpu)
+static void __activate_cptr_traps(struct kvm_vcpu *vcpu)
{
- u64 val;
+ u64 val = CPTR_EL2_TAM; /* Same bit irrespective of E2H */
- ___activate_traps(vcpu);
- __activate_traps_common(vcpu);
+ if (has_hvhe()) {
+ val |= CPACR_ELx_TTA;
- val = vcpu->arch.cptr_el2;
- val |= CPTR_EL2_TAM; /* Same bit irrespective of E2H */
- val |= has_hvhe() ? CPACR_EL1_TTA : CPTR_EL2_TTA;
- if (cpus_have_final_cap(ARM64_SME)) {
- if (has_hvhe())
- val &= ~(CPACR_EL1_SMEN_EL1EN | CPACR_EL1_SMEN_EL0EN);
- else
- val |= CPTR_EL2_TSM;
- }
+ if (guest_owns_fp_regs(vcpu)) {
+ val |= CPACR_ELx_FPEN;
+ if (vcpu_has_sve(vcpu))
+ val |= CPACR_ELx_ZEN;
+ }
+ } else {
+ val |= CPTR_EL2_TTA | CPTR_NVHE_EL2_RES1;
+
+ /*
+ * Always trap SME since it's not supported in KVM.
+ * TSM is RES1 if SME isn't implemented.
+ */
+ val |= CPTR_EL2_TSM;
- if (!guest_owns_fp_regs(vcpu)) {
- if (has_hvhe())
- val &= ~(CPACR_EL1_FPEN_EL0EN | CPACR_EL1_FPEN_EL1EN |
- CPACR_EL1_ZEN_EL0EN | CPACR_EL1_ZEN_EL1EN);
- else
- val |= CPTR_EL2_TFP | CPTR_EL2_TZ;
+ if (!vcpu_has_sve(vcpu) || !guest_owns_fp_regs(vcpu))
+ val |= CPTR_EL2_TZ;
- __activate_traps_fpsimd32(vcpu);
+ if (!guest_owns_fp_regs(vcpu))
+ val |= CPTR_EL2_TFP;
}
+ if (!guest_owns_fp_regs(vcpu))
+ __activate_traps_fpsimd32(vcpu);
+
kvm_write_cptr_el2(val);
+}
+
+static void __activate_traps(struct kvm_vcpu *vcpu)
+{
+ ___activate_traps(vcpu);
+ __activate_traps_common(vcpu);
+ __activate_cptr_traps(vcpu);
+
write_sysreg(__this_cpu_read(kvm_hyp_vector), vbar_el2);
if (cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT)) {
Patches currently in stable-queue which might be from broonie@kernel.org are
queue-6.6/kvm-arm64-calculate-cptr_el2-traps-on-activating-traps.patch
queue-6.6/regulator-check-that-dummy-regulator-has-been-probed-before-using-it.patch
queue-6.6/kvm-arm64-eagerly-switch-zcr_el-1-2.patch
queue-6.6/kvm-arm64-mark-some-header-functions-as-inline.patch
queue-6.6/kvm-arm64-remove-host-fpsimd-saving-for-non-protected-kvm.patch
queue-6.6/regulator-dummy-force-synchronous-probing.patch
queue-6.6/kvm-arm64-refactor-exit-handlers.patch
queue-6.6/kvm-arm64-unconditionally-save-flush-host-fpsimd-sve-sme-state.patch
queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.smen.patch
queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.zen.patch
^ permalink raw reply [flat|nested] 17+ messages in thread
* Patch "KVM: arm64: Eagerly switch ZCR_EL{1,2}" has been added to the 6.6-stable tree
2025-03-21 0:16 ` [PATCH 6.6 8/8] KVM: arm64: Eagerly switch ZCR_EL{1,2} Mark Brown
@ 2025-03-25 11:28 ` gregkh
0 siblings, 0 replies; 17+ messages in thread
From: gregkh @ 2025-03-25 11:28 UTC (permalink / raw)
To: broonie, catalin.marinas, gregkh, james.morse, kvmarm,
linux-arm-kernel, mark.rutland, maz, oliver.upton, suzuki.poulose,
tabba, will
Cc: stable-commits
This is a note to let you know that I've just added the patch titled
KVM: arm64: Eagerly switch ZCR_EL{1,2}
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-arm64-eagerly-switch-zcr_el-1-2.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
From broonie@kernel.org Thu Mar 20 20:18:40 2025
From: Mark Brown <broonie@kernel.org>
Date: Fri, 21 Mar 2025 00:16:08 +0000
Subject: KVM: arm64: Eagerly switch ZCR_EL{1,2}
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 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>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Mark Brown <broonie@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Fuad Tabba <tabba@google.com>
Message-ID: <20250321-stable-sve-6-6-v1-8-0b3a6a14ea53@kernel.org>
From: Mark Rutland <mark.rutland@arm.com>
[ Upstream commit 59419f10045bc955d2229819c7cf7a8b0b9c5b59 ]
In non-protected KVM modes, while the guest FPSIMD/SVE/SME state is live on the
CPU, the host's active SVE VL may differ from the guest's maximum SVE VL:
* For VHE hosts, when a VM uses NV, ZCR_EL2 contains a value constrained
by the guest hypervisor, which may be less than or equal to that
guest's maximum VL.
Note: in this case the value of ZCR_EL1 is immaterial due to E2H.
* For nVHE/hVHE hosts, ZCR_EL1 contains a value written by the guest,
which may be less than or greater than the guest's maximum VL.
Note: in this case hyp code traps host SVE usage and lazily restores
ZCR_EL2 to the host's maximum VL, which may be greater than the
guest's maximum VL.
This can be the case between exiting a guest and kvm_arch_vcpu_put_fp().
If a softirq is taken during this period and the softirq handler tries
to use kernel-mode NEON, then the kernel will fail to save the guest's
FPSIMD/SVE state, and will pend a SIGKILL for the current thread.
This happens because kvm_arch_vcpu_ctxsync_fp() binds the guest's live
FPSIMD/SVE state with the guest's maximum SVE VL, and
fpsimd_save_user_state() verifies that the live SVE VL is as expected
before attempting to save the register state:
| if (WARN_ON(sve_get_vl() != vl)) {
| force_signal_inject(SIGKILL, SI_KERNEL, 0, 0);
| return;
| }
Fix this and make this a bit easier to reason about by always eagerly
switching ZCR_EL{1,2} at hyp during guest<->host transitions. With this
happening, there's no need to trap host SVE usage, and the nVHE/nVHE
__deactivate_cptr_traps() logic can be simplified to enable host access
to all present FPSIMD/SVE/SME features.
In protected nVHE/hVHE modes, the host's state is always saved/restored
by hyp, and the guest's state is saved prior to exit to the host, so
from the host's PoV the guest never has live FPSIMD/SVE/SME state, and
the host's ZCR_EL1 is never clobbered by hyp.
Fixes: 8c8010d69c132273 ("KVM: arm64: Save/restore SVE state for nVHE")
Fixes: 2e3cf82063a00ea0 ("KVM: arm64: nv: Ensure correct VL is loaded before saving SVE state")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-9-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
[ v6.6 lacks pKVM saving of host SVE state, pull in discovery of maximum
host VL separately -- broonie ]
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/include/asm/kvm_host.h | 1
arch/arm64/include/asm/kvm_hyp.h | 1
arch/arm64/kvm/fpsimd.c | 19 +++++------
arch/arm64/kvm/hyp/entry.S | 5 ++
arch/arm64/kvm/hyp/include/hyp/switch.h | 55 ++++++++++++++++++++++++++++++++
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 12 +-----
arch/arm64/kvm/hyp/nvhe/pkvm.c | 2 +
arch/arm64/kvm/hyp/nvhe/switch.c | 33 ++++++++++++++++---
arch/arm64/kvm/hyp/vhe/switch.c | 4 ++
arch/arm64/kvm/reset.c | 3 +
10 files changed, 113 insertions(+), 22 deletions(-)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -73,6 +73,7 @@ static inline enum kvm_mode kvm_get_mode
#endif
extern unsigned int __ro_after_init kvm_sve_max_vl;
+extern unsigned int __ro_after_init kvm_host_sve_max_vl;
int __init kvm_arm_init_sve(void);
u32 __attribute_const__ kvm_target_cpu(void);
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -145,5 +145,6 @@ extern u64 kvm_nvhe_sym(id_aa64smfr0_el1
extern unsigned long kvm_nvhe_sym(__icache_flags);
extern unsigned int kvm_nvhe_sym(kvm_arm_vmid_bits);
+extern unsigned int kvm_nvhe_sym(kvm_host_sve_max_vl);
#endif /* __ARM64_KVM_HYP_H__ */
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -152,15 +152,16 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcp
local_irq_save(flags);
if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED) {
- if (vcpu_has_sve(vcpu)) {
- __vcpu_sys_reg(vcpu, ZCR_EL1) = read_sysreg_el1(SYS_ZCR);
-
- /* Restore the VL that was saved when bound to the CPU */
- if (!has_vhe())
- sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1,
- SYS_ZCR_EL1);
- }
-
+ /*
+ * Flush (save and invalidate) the fpsimd/sve state so that if
+ * the host tries to use fpsimd/sve, it's not using stale data
+ * from the guest.
+ *
+ * Flushing the state sets the TIF_FOREIGN_FPSTATE bit for the
+ * context unconditionally, in both nVHE and VHE. This allows
+ * the kernel to restore the fpsimd/sve state, including ZCR_EL1
+ * when needed.
+ */
fpsimd_save_and_flush_cpu_state();
}
--- a/arch/arm64/kvm/hyp/entry.S
+++ b/arch/arm64/kvm/hyp/entry.S
@@ -44,6 +44,11 @@ alternative_if ARM64_HAS_RAS_EXTN
alternative_else_nop_endif
mrs x1, isr_el1
cbz x1, 1f
+
+ // Ensure that __guest_enter() always provides a context
+ // synchronization event so that callers don't need ISBs for anything
+ // that would usually be synchonized by the ERET.
+ isb
mov x0, #ARM_EXCEPTION_IRQ
ret
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -273,6 +273,61 @@ static inline void __hyp_sve_restore_gue
write_sysreg_el1(__vcpu_sys_reg(vcpu, ZCR_EL1), SYS_ZCR);
}
+static inline void fpsimd_lazy_switch_to_guest(struct kvm_vcpu *vcpu)
+{
+ u64 zcr_el1, zcr_el2;
+
+ if (!guest_owns_fp_regs(vcpu))
+ return;
+
+ if (vcpu_has_sve(vcpu)) {
+ zcr_el2 = vcpu_sve_max_vq(vcpu) - 1;
+
+ write_sysreg_el2(zcr_el2, SYS_ZCR);
+
+ zcr_el1 = __vcpu_sys_reg(vcpu, ZCR_EL1);
+ write_sysreg_el1(zcr_el1, SYS_ZCR);
+ }
+}
+
+static inline void fpsimd_lazy_switch_to_host(struct kvm_vcpu *vcpu)
+{
+ u64 zcr_el1, zcr_el2;
+
+ if (!guest_owns_fp_regs(vcpu))
+ return;
+
+ /*
+ * When the guest owns the FP regs, we know that guest+hyp traps for
+ * any FPSIMD/SVE/SME features exposed to the guest have been disabled
+ * by either fpsimd_lazy_switch_to_guest() or kvm_hyp_handle_fpsimd()
+ * prior to __guest_entry(). As __guest_entry() guarantees a context
+ * synchronization event, we don't need an ISB here to avoid taking
+ * traps for anything that was exposed to the guest.
+ */
+ if (vcpu_has_sve(vcpu)) {
+ zcr_el1 = read_sysreg_el1(SYS_ZCR);
+ __vcpu_sys_reg(vcpu, ZCR_EL1) = zcr_el1;
+
+ /*
+ * The guest's state is always saved using the guest's max VL.
+ * Ensure that the host has the guest's max VL active such that
+ * the host can save the guest's state lazily, but don't
+ * artificially restrict the host to the guest's max VL.
+ */
+ if (has_vhe()) {
+ zcr_el2 = vcpu_sve_max_vq(vcpu) - 1;
+ write_sysreg_el2(zcr_el2, SYS_ZCR);
+ } else {
+ zcr_el2 = sve_vq_from_vl(kvm_host_sve_max_vl) - 1;
+ write_sysreg_el2(zcr_el2, SYS_ZCR);
+
+ zcr_el1 = vcpu_sve_max_vq(vcpu) - 1;
+ write_sysreg_el1(zcr_el1, SYS_ZCR);
+ }
+ }
+}
+
/*
* We trap the first access to the FP/SIMD to save the host context and
* restore the guest context lazily.
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -5,6 +5,7 @@
*/
#include <hyp/adjust_pc.h>
+#include <hyp/switch.h>
#include <asm/pgtable-types.h>
#include <asm/kvm_asm.h>
@@ -95,7 +96,9 @@ static void handle___kvm_vcpu_run(struct
pkvm_put_hyp_vcpu(hyp_vcpu);
} else {
/* The host is fully trusted, run its vCPU directly. */
+ fpsimd_lazy_switch_to_guest(host_vcpu);
ret = __kvm_vcpu_run(host_vcpu);
+ fpsimd_lazy_switch_to_host(host_vcpu);
}
out:
@@ -416,15 +419,6 @@ void handle_trap(struct kvm_cpu_context
case ESR_ELx_EC_SMC64:
handle_host_smc(host_ctxt);
break;
- case ESR_ELx_EC_SVE:
- if (has_hvhe())
- sysreg_clear_set(cpacr_el1, 0, (CPACR_EL1_ZEN_EL1EN |
- CPACR_EL1_ZEN_EL0EN));
- else
- sysreg_clear_set(cptr_el2, CPTR_EL2_TZ, 0);
- isb();
- sve_cond_update_zcr_vq(ZCR_ELx_LEN_MASK, SYS_ZCR_EL2);
- break;
case ESR_ELx_EC_IABT_LOW:
case ESR_ELx_EC_DABT_LOW:
handle_host_mem_abort(host_ctxt);
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
@@ -18,6 +18,8 @@ unsigned long __icache_flags;
/* Used by kvm_get_vttbr(). */
unsigned int kvm_arm_vmid_bits;
+unsigned int kvm_host_sve_max_vl;
+
/*
* Set trap register values based on features in ID_AA64PFR0.
*/
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -40,6 +40,9 @@ static void __activate_cptr_traps(struct
{
u64 val = CPTR_EL2_TAM; /* Same bit irrespective of E2H */
+ if (!guest_owns_fp_regs(vcpu))
+ __activate_traps_fpsimd32(vcpu);
+
if (has_hvhe()) {
val |= CPACR_ELx_TTA;
@@ -48,6 +51,8 @@ static void __activate_cptr_traps(struct
if (vcpu_has_sve(vcpu))
val |= CPACR_ELx_ZEN;
}
+
+ write_sysreg(val, cpacr_el1);
} else {
val |= CPTR_EL2_TTA | CPTR_NVHE_EL2_RES1;
@@ -62,12 +67,32 @@ static void __activate_cptr_traps(struct
if (!guest_owns_fp_regs(vcpu))
val |= CPTR_EL2_TFP;
+
+ write_sysreg(val, cptr_el2);
}
+}
- if (!guest_owns_fp_regs(vcpu))
- __activate_traps_fpsimd32(vcpu);
+static void __deactivate_cptr_traps(struct kvm_vcpu *vcpu)
+{
+ if (has_hvhe()) {
+ u64 val = CPACR_ELx_FPEN;
+
+ if (cpus_have_final_cap(ARM64_SVE))
+ val |= CPACR_ELx_ZEN;
+ if (cpus_have_final_cap(ARM64_SME))
+ val |= CPACR_ELx_SMEN;
+
+ write_sysreg(val, cpacr_el1);
+ } else {
+ u64 val = CPTR_NVHE_EL2_RES1;
+
+ if (!cpus_have_final_cap(ARM64_SVE))
+ val |= CPTR_EL2_TZ;
+ if (!cpus_have_final_cap(ARM64_SME))
+ val |= CPTR_EL2_TSM;
- kvm_write_cptr_el2(val);
+ write_sysreg(val, cptr_el2);
+ }
}
static void __activate_traps(struct kvm_vcpu *vcpu)
@@ -120,7 +145,7 @@ static void __deactivate_traps(struct kv
write_sysreg(this_cpu_ptr(&kvm_init_params)->hcr_el2, hcr_el2);
- kvm_reset_cptr_el2(vcpu);
+ __deactivate_cptr_traps(vcpu);
write_sysreg(__kvm_hyp_host_vector, vbar_el2);
}
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -212,6 +212,8 @@ static int __kvm_vcpu_run_vhe(struct kvm
sysreg_save_host_state_vhe(host_ctxt);
+ fpsimd_lazy_switch_to_guest(vcpu);
+
/*
* ARM erratum 1165522 requires us to configure both stage 1 and
* stage 2 translation for the guest context before we clear
@@ -247,6 +249,8 @@ static int __kvm_vcpu_run_vhe(struct kvm
__deactivate_traps(vcpu);
+ fpsimd_lazy_switch_to_host(vcpu);
+
sysreg_restore_host_state_vhe(host_ctxt);
if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED)
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -46,11 +46,14 @@ static u32 __ro_after_init kvm_ipa_limit
PSR_AA32_I_BIT | PSR_AA32_F_BIT)
unsigned int __ro_after_init kvm_sve_max_vl;
+unsigned int __ro_after_init kvm_host_sve_max_vl;
int __init kvm_arm_init_sve(void)
{
if (system_supports_sve()) {
kvm_sve_max_vl = sve_max_virtualisable_vl();
+ kvm_host_sve_max_vl = sve_max_vl();
+ kvm_nvhe_sym(kvm_host_sve_max_vl) = kvm_host_sve_max_vl;
/*
* The get_sve_reg()/set_sve_reg() ioctl interface will need
Patches currently in stable-queue which might be from broonie@kernel.org are
queue-6.6/kvm-arm64-calculate-cptr_el2-traps-on-activating-traps.patch
queue-6.6/regulator-check-that-dummy-regulator-has-been-probed-before-using-it.patch
queue-6.6/kvm-arm64-eagerly-switch-zcr_el-1-2.patch
queue-6.6/kvm-arm64-mark-some-header-functions-as-inline.patch
queue-6.6/kvm-arm64-remove-host-fpsimd-saving-for-non-protected-kvm.patch
queue-6.6/regulator-dummy-force-synchronous-probing.patch
queue-6.6/kvm-arm64-refactor-exit-handlers.patch
queue-6.6/kvm-arm64-unconditionally-save-flush-host-fpsimd-sve-sme-state.patch
queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.smen.patch
queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.zen.patch
^ permalink raw reply [flat|nested] 17+ messages in thread
* Patch "KVM: arm64: Refactor exit handlers" has been added to the 6.6-stable tree
2025-03-21 0:16 ` [PATCH 6.6 6/8] KVM: arm64: Refactor exit handlers Mark Brown
@ 2025-03-25 11:28 ` gregkh
0 siblings, 0 replies; 17+ messages in thread
From: gregkh @ 2025-03-25 11:28 UTC (permalink / raw)
To: broonie, catalin.marinas, gregkh, james.morse, kvmarm,
linux-arm-kernel, mark.rutland, maz, oliver.upton, suzuki.poulose,
tabba, will
Cc: stable-commits
This is a note to let you know that I've just added the patch titled
KVM: arm64: Refactor exit handlers
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-arm64-refactor-exit-handlers.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
From broonie@kernel.org Thu Mar 20 20:18:34 2025
From: Mark Brown <broonie@kernel.org>
Date: Fri, 21 Mar 2025 00:16:06 +0000
Subject: KVM: arm64: Refactor exit handlers
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 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>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Mark Brown <broonie@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Fuad Tabba <tabba@google.com>
Message-ID: <20250321-stable-sve-6-6-v1-6-0b3a6a14ea53@kernel.org>
From: Mark Rutland <mark.rutland@arm.com>
[ Upstream commit 9b66195063c5a145843547b1d692bd189be85287 ]
The hyp exit handling logic is largely shared between VHE and nVHE/hVHE,
with common logic in arch/arm64/kvm/hyp/include/hyp/switch.h. The code
in the header depends on function definitions provided by
arch/arm64/kvm/hyp/vhe/switch.c and arch/arm64/kvm/hyp/nvhe/switch.c
when they include the header.
This is an unusual header dependency, and prevents the use of
arch/arm64/kvm/hyp/include/hyp/switch.h in other files as this would
result in compiler warnings regarding missing definitions, e.g.
| In file included from arch/arm64/kvm/hyp/nvhe/hyp-main.c:8:
| ./arch/arm64/kvm/hyp/include/hyp/switch.h:733:31: warning: 'kvm_get_exit_handler_array' used but never defined
| 733 | static const exit_handler_fn *kvm_get_exit_handler_array(struct kvm_vcpu *vcpu);
| | ^~~~~~~~~~~~~~~~~~~~~~~~~~
| ./arch/arm64/kvm/hyp/include/hyp/switch.h:735:13: warning: 'early_exit_filter' used but never defined
| 735 | static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code);
| | ^~~~~~~~~~~~~~~~~
Refactor the logic such that the header doesn't depend on anything from
the C files. There should be no functional change as a result of this
patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-7-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/kvm/hyp/include/hyp/switch.h | 30 ++++++------------------------
arch/arm64/kvm/hyp/nvhe/switch.c | 27 +++++++++++++++------------
arch/arm64/kvm/hyp/vhe/switch.c | 9 ++++-----
3 files changed, 25 insertions(+), 41 deletions(-)
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -592,23 +592,16 @@ static bool kvm_hyp_handle_dabt_low(stru
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.
*
* Returns true if the hypervisor handled the exit, and control should go back
* to the guest, or false if it hasn't.
*/
-static inline bool kvm_hyp_handle_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
+static inline bool kvm_hyp_handle_exit(struct kvm_vcpu *vcpu, u64 *exit_code,
+ const exit_handler_fn *handlers)
{
- const exit_handler_fn *handlers = kvm_get_exit_handler_array(vcpu);
- exit_handler_fn fn;
-
- fn = handlers[kvm_vcpu_trap_get_class(vcpu)];
-
+ exit_handler_fn fn = handlers[kvm_vcpu_trap_get_class(vcpu)];
if (fn)
return fn(vcpu, exit_code);
@@ -638,20 +631,9 @@ static inline void synchronize_vcpu_psta
* the guest, false when we should restore the host state and return to the
* main run loop.
*/
-static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
+static inline bool __fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code,
+ const exit_handler_fn *handlers)
{
- /*
- * Save PSTATE early so that we can evaluate the vcpu mode
- * early on.
- */
- synchronize_vcpu_pstate(vcpu, exit_code);
-
- /*
- * 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);
@@ -681,7 +663,7 @@ static inline bool fixup_guest_exit(stru
goto exit;
/* Check if there's an exit handler and allow it to handle the exit. */
- if (kvm_hyp_handle_exit(vcpu, exit_code))
+ if (kvm_hyp_handle_exit(vcpu, exit_code, handlers))
goto guest;
exit:
/* Return to the host kernel and handle the exit */
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -225,21 +225,22 @@ static const exit_handler_fn *kvm_get_ex
return hyp_exit_handlers;
}
-/*
- * Some guests (e.g., protected VMs) are not be allowed to run in AArch32.
- * The ARMv8 architecture does not give the hypervisor a mechanism to prevent a
- * guest from dropping to AArch32 EL0 if implemented by the CPU. If the
- * hypervisor spots a guest in such a state ensure it is handled, and don't
- * trust the host to spot or fix it. The check below is based on the one in
- * kvm_arch_vcpu_ioctl_run().
- *
- * 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 void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code)
+static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
{
+ const exit_handler_fn *handlers = kvm_get_exit_handler_array(vcpu);
struct kvm *kvm = kern_hyp_va(vcpu->kvm);
+ synchronize_vcpu_pstate(vcpu, exit_code);
+
+ /*
+ * Some guests (e.g., protected VMs) are not be allowed to run in
+ * AArch32. The ARMv8 architecture does not give the hypervisor a
+ * mechanism to prevent a guest from dropping to AArch32 EL0 if
+ * implemented by the CPU. If the hypervisor spots a guest in such a
+ * state ensure it is handled, and don't trust the host to spot or fix
+ * it. The check below is based on the one in
+ * kvm_arch_vcpu_ioctl_run().
+ */
if (kvm_vm_is_protected(kvm) && vcpu_mode_is_32bit(vcpu)) {
/*
* As we have caught the guest red-handed, decide that it isn't
@@ -252,6 +253,8 @@ static void early_exit_filter(struct kvm
*exit_code &= BIT(ARM_EXIT_WITH_SERROR_BIT);
*exit_code |= ARM_EXCEPTION_IL;
}
+
+ return __fixup_guest_exit(vcpu, exit_code, handlers);
}
/* Switch to the guest for legacy non-VHE systems */
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -172,13 +172,10 @@ static const exit_handler_fn hyp_exit_ha
[ESR_ELx_EC_PAC] = kvm_hyp_handle_ptrauth,
};
-static const exit_handler_fn *kvm_get_exit_handler_array(struct kvm_vcpu *vcpu)
+static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
{
- return hyp_exit_handlers;
-}
+ synchronize_vcpu_pstate(vcpu, exit_code);
-static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code)
-{
/*
* If we were in HYP context on entry, adjust the PSTATE view
* so that the usual helpers work correctly.
@@ -198,6 +195,8 @@ static void early_exit_filter(struct kvm
*vcpu_cpsr(vcpu) &= ~(PSR_MODE_MASK | PSR_MODE32_BIT);
*vcpu_cpsr(vcpu) |= mode;
}
+
+ return __fixup_guest_exit(vcpu, exit_code, hyp_exit_handlers);
}
/* Switch to the guest for VHE systems running in EL2 */
Patches currently in stable-queue which might be from broonie@kernel.org are
queue-6.6/kvm-arm64-calculate-cptr_el2-traps-on-activating-traps.patch
queue-6.6/regulator-check-that-dummy-regulator-has-been-probed-before-using-it.patch
queue-6.6/kvm-arm64-eagerly-switch-zcr_el-1-2.patch
queue-6.6/kvm-arm64-mark-some-header-functions-as-inline.patch
queue-6.6/kvm-arm64-remove-host-fpsimd-saving-for-non-protected-kvm.patch
queue-6.6/regulator-dummy-force-synchronous-probing.patch
queue-6.6/kvm-arm64-refactor-exit-handlers.patch
queue-6.6/kvm-arm64-unconditionally-save-flush-host-fpsimd-sve-sme-state.patch
queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.smen.patch
queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.zen.patch
^ permalink raw reply [flat|nested] 17+ messages in thread
* Patch "KVM: arm64: Remove host FPSIMD saving for non-protected KVM" has been added to the 6.6-stable tree
2025-03-21 0:16 ` [PATCH 6.6 3/8] KVM: arm64: Remove host FPSIMD saving for non-protected KVM Mark Brown
@ 2025-03-25 11:28 ` gregkh
0 siblings, 0 replies; 17+ messages in thread
From: gregkh @ 2025-03-25 11:28 UTC (permalink / raw)
To: broonie, catalin.marinas, gregkh, james.morse, kvmarm,
linux-arm-kernel, mark.rutland, maz, oliver.upton, suzuki.poulose,
tabba, will
Cc: stable-commits
This is a note to let you know that I've just added the patch titled
KVM: arm64: Remove host FPSIMD saving for non-protected KVM
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-arm64-remove-host-fpsimd-saving-for-non-protected-kvm.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
From stable+bounces-125721-greg=kroah.com@vger.kernel.org Thu Mar 20 20:20:22 2025
From: Mark Brown <broonie@kernel.org>
Date: Fri, 21 Mar 2025 00:16:03 +0000
Subject: KVM: arm64: Remove host FPSIMD saving for non-protected KVM
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 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>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Mark Brown <broonie@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Fuad Tabba <tabba@google.com>
Message-ID: <20250321-stable-sve-6-6-v1-3-0b3a6a14ea53@kernel.org>
From: Mark Rutland <mark.rutland@arm.com>
[ Upstream commit 8eca7f6d5100b6997df4f532090bc3f7e0203bef ]
Now that the host eagerly saves its own FPSIMD/SVE/SME state,
non-protected KVM never needs to save the host FPSIMD/SVE/SME state,
and the code to do this is never used. Protected KVM still needs to
save/restore the host FPSIMD/SVE state to avoid leaking guest state to
the host (and to avoid revealing to the host whether the guest used
FPSIMD/SVE/SME), and that code needs to be retained.
Remove the unused code and data structures.
To avoid the need for a stub copy of kvm_hyp_save_fpsimd_host() in the
VHE hyp code, the nVHE/hVHE version is moved into the shared switch
header, where it is only invoked when KVM is in protected mode.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-3-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/include/asm/kvm_host.h | 1 -
arch/arm64/kvm/fpsimd.c | 2 --
arch/arm64/kvm/hyp/include/hyp/switch.h | 4 ----
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 1 -
4 files changed, 8 deletions(-)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -535,7 +535,6 @@ struct kvm_vcpu_arch {
struct kvm_guest_debug_arch vcpu_debug_state;
struct kvm_guest_debug_arch external_debug_state;
- struct user_fpsimd_state *host_fpsimd_state; /* hyp VA */
struct task_struct *parent_task;
struct {
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -49,8 +49,6 @@ int kvm_arch_vcpu_run_map_fp(struct kvm_
if (ret)
return ret;
- vcpu->arch.host_fpsimd_state = kern_hyp_va(fpsimd);
-
/*
* We need to keep current's task_struct pinned until its data has been
* unshared with the hypervisor to make sure it is not re-used by the
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -321,10 +321,6 @@ static bool kvm_hyp_handle_fpsimd(struct
}
isb();
- /* Write out the host state if it's in the registers */
- if (vcpu->arch.fp_state == FP_STATE_HOST_OWNED)
- __fpsimd_save_state(vcpu->arch.host_fpsimd_state);
-
/* Restore the guest state */
if (sve_guest)
__hyp_sve_restore_guest(vcpu);
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -41,7 +41,6 @@ static void flush_hyp_vcpu(struct pkvm_h
hyp_vcpu->vcpu.arch.fp_state = host_vcpu->arch.fp_state;
hyp_vcpu->vcpu.arch.debug_ptr = kern_hyp_va(host_vcpu->arch.debug_ptr);
- hyp_vcpu->vcpu.arch.host_fpsimd_state = host_vcpu->arch.host_fpsimd_state;
hyp_vcpu->vcpu.arch.vsesr_el2 = host_vcpu->arch.vsesr_el2;
Patches currently in stable-queue which might be from broonie@kernel.org are
queue-6.6/kvm-arm64-calculate-cptr_el2-traps-on-activating-traps.patch
queue-6.6/regulator-check-that-dummy-regulator-has-been-probed-before-using-it.patch
queue-6.6/kvm-arm64-eagerly-switch-zcr_el-1-2.patch
queue-6.6/kvm-arm64-mark-some-header-functions-as-inline.patch
queue-6.6/kvm-arm64-remove-host-fpsimd-saving-for-non-protected-kvm.patch
queue-6.6/regulator-dummy-force-synchronous-probing.patch
queue-6.6/kvm-arm64-refactor-exit-handlers.patch
queue-6.6/kvm-arm64-unconditionally-save-flush-host-fpsimd-sve-sme-state.patch
queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.smen.patch
queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.zen.patch
^ permalink raw reply [flat|nested] 17+ messages in thread
* Patch "KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN" has been added to the 6.6-stable tree
2025-03-21 0:16 ` [PATCH 6.6 5/8] KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN Mark Brown
@ 2025-03-25 11:28 ` gregkh
0 siblings, 0 replies; 17+ messages in thread
From: gregkh @ 2025-03-25 11:28 UTC (permalink / raw)
To: broonie, catalin.marinas, gregkh, james.morse, kvmarm,
linux-arm-kernel, mark.rutland, maz, oliver.upton, suzuki.poulose,
tabba, will
Cc: stable-commits
This is a note to let you know that I've just added the patch titled
KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.smen.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
From broonie@kernel.org Thu Mar 20 20:18:32 2025
From: Mark Brown <broonie@kernel.org>
Date: Fri, 21 Mar 2025 00:16:05 +0000
Subject: KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 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>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Mark Brown <broonie@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Fuad Tabba <tabba@google.com>
Message-ID: <20250321-stable-sve-6-6-v1-5-0b3a6a14ea53@kernel.org>
From: Mark Rutland <mark.rutland@arm.com>
[ Upstream commit 407a99c4654e8ea65393f412c421a55cac539f5b ]
When KVM is in VHE mode, the host kernel tries to save and restore the
configuration of CPACR_EL1.SMEN (i.e. CPTR_EL2.SMEN when HCR_EL2.E2H=1)
across kvm_arch_vcpu_load_fp() and kvm_arch_vcpu_put_fp(), since the
configuration may be clobbered by hyp when running a vCPU. This logic
has historically been broken, and is currently redundant.
This logic was originally introduced in commit:
861262ab86270206 ("KVM: arm64: Handle SME host state when running guests")
At the time, the VHE hyp code would reset CPTR_EL2.SMEN to 0b00 when
returning to the host, trapping host access to SME state. Unfortunately,
this was unsafe as the host could take a softirq before calling
kvm_arch_vcpu_put_fp(), and if a softirq handler were to use kernel mode
NEON the resulting attempt to save the live FPSIMD/SVE/SME state would
result in a fatal trap.
That issue was limited to VHE mode. For nVHE/hVHE modes, KVM always
saved/restored the host kernel's CPACR_EL1 value, and configured
CPTR_EL2.TSM to 0b0, ensuring that host usage of SME would not be
trapped.
The issue above was incidentally fixed by commit:
375110ab51dec5dc ("KVM: arm64: Fix resetting SME trap values on reset for (h)VHE")
That commit changed the VHE hyp code to configure CPTR_EL2.SMEN to 0b01
when returning to the host, permitting host kernel usage of SME,
avoiding the issue described above. At the time, this was not identified
as a fix for commit 861262ab86270206.
Now that the host eagerly saves and unbinds its own FPSIMD/SVE/SME
state, there's no need to save/restore the state of the EL0 SME trap.
The kernel can safely save/restore state without trapping, as described
above, and will restore userspace state (including trap controls) before
returning to userspace.
Remove the redundant logic.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-5-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
[Update for rework of flags storage -- broonie]
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/include/asm/kvm_host.h | 2 --
arch/arm64/kvm/fpsimd.c | 23 -----------------------
2 files changed, 25 deletions(-)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -717,8 +717,6 @@ struct kvm_vcpu_arch {
/* vcpu running in HYP context */
#define VCPU_HYP_CONTEXT __vcpu_single_flag(iflags, BIT(7))
-/* SME enabled for EL0 */
-#define HOST_SME_ENABLED __vcpu_single_flag(sflags, BIT(1))
/* Physical CPU not in supported_cpus */
#define ON_UNSUPPORTED_CPU __vcpu_single_flag(sflags, BIT(2))
/* WFIT instruction trapped */
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -87,12 +87,6 @@ void kvm_arch_vcpu_load_fp(struct kvm_vc
*/
fpsimd_save_and_flush_cpu_state();
vcpu->arch.fp_state = FP_STATE_FREE;
-
- if (system_supports_sme()) {
- vcpu_clear_flag(vcpu, HOST_SME_ENABLED);
- if (read_sysreg(cpacr_el1) & CPACR_EL1_SMEN_EL0EN)
- vcpu_set_flag(vcpu, HOST_SME_ENABLED);
- }
}
/*
@@ -157,23 +151,6 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcp
local_irq_save(flags);
- /*
- * If we have VHE then the Hyp code will reset CPACR_EL1 to
- * the default value and we need to reenable SME.
- */
- if (has_vhe() && system_supports_sme()) {
- /* Also restore EL0 state seen on entry */
- if (vcpu_get_flag(vcpu, HOST_SME_ENABLED))
- sysreg_clear_set(CPACR_EL1, 0,
- CPACR_EL1_SMEN_EL0EN |
- CPACR_EL1_SMEN_EL1EN);
- else
- sysreg_clear_set(CPACR_EL1,
- CPACR_EL1_SMEN_EL0EN,
- CPACR_EL1_SMEN_EL1EN);
- isb();
- }
-
if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED) {
if (vcpu_has_sve(vcpu)) {
__vcpu_sys_reg(vcpu, ZCR_EL1) = read_sysreg_el1(SYS_ZCR);
Patches currently in stable-queue which might be from broonie@kernel.org are
queue-6.6/kvm-arm64-calculate-cptr_el2-traps-on-activating-traps.patch
queue-6.6/regulator-check-that-dummy-regulator-has-been-probed-before-using-it.patch
queue-6.6/kvm-arm64-eagerly-switch-zcr_el-1-2.patch
queue-6.6/kvm-arm64-mark-some-header-functions-as-inline.patch
queue-6.6/kvm-arm64-remove-host-fpsimd-saving-for-non-protected-kvm.patch
queue-6.6/regulator-dummy-force-synchronous-probing.patch
queue-6.6/kvm-arm64-refactor-exit-handlers.patch
queue-6.6/kvm-arm64-unconditionally-save-flush-host-fpsimd-sve-sme-state.patch
queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.smen.patch
queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.zen.patch
^ permalink raw reply [flat|nested] 17+ messages in thread
* Patch "KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN" has been added to the 6.6-stable tree
2025-03-21 0:16 ` [PATCH 6.6 4/8] KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN Mark Brown
@ 2025-03-25 11:28 ` gregkh
0 siblings, 0 replies; 17+ messages in thread
From: gregkh @ 2025-03-25 11:28 UTC (permalink / raw)
To: broonie, catalin.marinas, gregkh, james.morse, kvmarm,
linux-arm-kernel, mark.rutland, maz, oliver.upton, suzuki.poulose,
tabba, will
Cc: stable-commits
This is a note to let you know that I've just added the patch titled
KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.zen.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
From broonie@kernel.org Thu Mar 20 20:18:28 2025
From: Mark Brown <broonie@kernel.org>
Date: Fri, 21 Mar 2025 00:16:04 +0000
Subject: KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 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>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Mark Brown <broonie@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Fuad Tabba <tabba@google.com>
Message-ID: <20250321-stable-sve-6-6-v1-4-0b3a6a14ea53@kernel.org>
From: Mark Rutland <mark.rutland@arm.com>
[ Upstream commit 459f059be702056d91537b99a129994aa6ccdd35 ]
When KVM is in VHE mode, the host kernel tries to save and restore the
configuration of CPACR_EL1.ZEN (i.e. CPTR_EL2.ZEN when HCR_EL2.E2H=1)
across kvm_arch_vcpu_load_fp() and kvm_arch_vcpu_put_fp(), since the
configuration may be clobbered by hyp when running a vCPU. This logic is
currently redundant.
The VHE hyp code unconditionally configures CPTR_EL2.ZEN to 0b01 when
returning to the host, permitting host kernel usage of SVE.
Now that the host eagerly saves and unbinds its own FPSIMD/SVE/SME
state, there's no need to save/restore the state of the EL0 SVE trap.
The kernel can safely save/restore state without trapping, as described
above, and will restore userspace state (including trap controls) before
returning to userspace.
Remove the redundant logic.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-4-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
[Rework for refactoring of where the flags are stored -- broonie]
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/include/asm/kvm_host.h | 2 --
arch/arm64/kvm/fpsimd.c | 16 ----------------
2 files changed, 18 deletions(-)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -717,8 +717,6 @@ struct kvm_vcpu_arch {
/* vcpu running in HYP context */
#define VCPU_HYP_CONTEXT __vcpu_single_flag(iflags, BIT(7))
-/* SVE enabled for host EL0 */
-#define HOST_SVE_ENABLED __vcpu_single_flag(sflags, BIT(0))
/* SME enabled for EL0 */
#define HOST_SME_ENABLED __vcpu_single_flag(sflags, BIT(1))
/* Physical CPU not in supported_cpus */
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -88,10 +88,6 @@ void kvm_arch_vcpu_load_fp(struct kvm_vc
fpsimd_save_and_flush_cpu_state();
vcpu->arch.fp_state = FP_STATE_FREE;
- vcpu_clear_flag(vcpu, HOST_SVE_ENABLED);
- if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN)
- vcpu_set_flag(vcpu, HOST_SVE_ENABLED);
-
if (system_supports_sme()) {
vcpu_clear_flag(vcpu, HOST_SME_ENABLED);
if (read_sysreg(cpacr_el1) & CPACR_EL1_SMEN_EL0EN)
@@ -189,18 +185,6 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcp
}
fpsimd_save_and_flush_cpu_state();
- } else if (has_vhe() && system_supports_sve()) {
- /*
- * The FPSIMD/SVE state in the CPU has not been touched, and we
- * have SVE (and VHE): CPACR_EL1 (alias CPTR_EL2) has been
- * reset by kvm_reset_cptr_el2() in the Hyp code, disabling SVE
- * for EL0. To avoid spurious traps, restore the trap state
- * seen by kvm_arch_vcpu_load_fp():
- */
- if (vcpu_get_flag(vcpu, HOST_SVE_ENABLED))
- sysreg_clear_set(CPACR_EL1, 0, CPACR_EL1_ZEN_EL0EN);
- else
- sysreg_clear_set(CPACR_EL1, CPACR_EL1_ZEN_EL0EN, 0);
}
local_irq_restore(flags);
Patches currently in stable-queue which might be from broonie@kernel.org are
queue-6.6/kvm-arm64-calculate-cptr_el2-traps-on-activating-traps.patch
queue-6.6/regulator-check-that-dummy-regulator-has-been-probed-before-using-it.patch
queue-6.6/kvm-arm64-eagerly-switch-zcr_el-1-2.patch
queue-6.6/kvm-arm64-mark-some-header-functions-as-inline.patch
queue-6.6/kvm-arm64-remove-host-fpsimd-saving-for-non-protected-kvm.patch
queue-6.6/regulator-dummy-force-synchronous-probing.patch
queue-6.6/kvm-arm64-refactor-exit-handlers.patch
queue-6.6/kvm-arm64-unconditionally-save-flush-host-fpsimd-sve-sme-state.patch
queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.smen.patch
queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.zen.patch
^ permalink raw reply [flat|nested] 17+ messages in thread
* Patch "KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state" has been added to the 6.6-stable tree
2025-03-21 0:16 ` [PATCH 6.6 2/8] KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state Mark Brown
@ 2025-03-25 11:28 ` gregkh
0 siblings, 0 replies; 17+ messages in thread
From: gregkh @ 2025-03-25 11:28 UTC (permalink / raw)
To: broonie, catalin.marinas, eauger, eric.auger, fweimer, gregkh,
james.morse, jeremy.linton, kvmarm, linux-arm-kernel,
mark.rutland, maz, oliver.upton, pbonzini, suzuki.poulose, tabba,
wilco.dijkstra, will
Cc: stable-commits
This is a note to let you know that I've just added the patch titled
KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-arm64-unconditionally-save-flush-host-fpsimd-sve-sme-state.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
From stable+bounces-125720-greg=kroah.com@vger.kernel.org Thu Mar 20 20:18:53 2025
From: Mark Brown <broonie@kernel.org>
Date: Fri, 21 Mar 2025 00:16:02 +0000
Subject: KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 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>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Mark Brown <broonie@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Eric Auger <eauger@redhat.com>, Wilco Dijkstra <wilco.dijkstra@arm.com>, Eric Auger <eric.auger@redhat.com>, Florian Weimer <fweimer@redhat.com>, Fuad Tabba <tabba@google.com>, Jeremy Linton <jeremy.linton@arm.com>, Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20250321-stable-sve-6-6-v1-2-0b3a6a14ea53@kernel.org>
From: Mark Rutland <mark.rutland@arm.com>
[ Upstream commit fbc7e61195e23f744814e78524b73b59faa54ab4 ]
There are several problems with the way hyp code lazily saves the host's
FPSIMD/SVE state, including:
* Host SVE being discarded unexpectedly due to inconsistent
configuration of TIF_SVE and CPACR_ELx.ZEN. This has been seen to
result in QEMU crashes where SVE is used by memmove(), as reported by
Eric Auger:
https://issues.redhat.com/browse/RHEL-68997
* Host SVE state is discarded *after* modification by ptrace, which was an
unintentional ptrace ABI change introduced with lazy discarding of SVE state.
* The host FPMR value can be discarded when running a non-protected VM,
where FPMR support is not exposed to a VM, and that VM uses
FPSIMD/SVE. In these cases the hyp code does not save the host's FPMR
before unbinding the host's FPSIMD/SVE/SME state, leaving a stale
value in memory.
Avoid these by eagerly saving and "flushing" the host's FPSIMD/SVE/SME
state when loading a vCPU such that KVM does not need to save any of the
host's FPSIMD/SVE/SME state. For clarity, fpsimd_kvm_prepare() is
removed and the necessary call to fpsimd_save_and_flush_cpu_state() is
placed in kvm_arch_vcpu_load_fp(). As 'fpsimd_state' and 'fpmr_ptr'
should not be used, they are set to NULL; all uses of these will be
removed in subsequent patches.
Historical problems go back at least as far as v5.17, e.g. erroneous
assumptions about TIF_SVE being clear in commit:
8383741ab2e773a9 ("KVM: arm64: Get rid of host SVE tracking/saving")
... and so this eager save+flush probably needs to be backported to ALL
stable trees.
Fixes: 93ae6b01bafee8fa ("KVM: arm64: Discard any SVE state when entering KVM guests")
Fixes: 8c845e2731041f0f ("arm64/sve: Leave SVE enabled on syscall if we don't context switch")
Fixes: ef3be86021c3bdf3 ("KVM: arm64: Add save/restore support for FPMR")
Reported-by: Eric Auger <eauger@redhat.com>
Reported-by: Wilco Dijkstra <wilco.dijkstra@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Tested-by: Eric Auger <eric.auger@redhat.com>
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Jeremy Linton <jeremy.linton@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-2-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
[ Mark: Handle vcpu/host flag conflict ]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/kernel/fpsimd.c | 25 -------------------------
arch/arm64/kvm/fpsimd.c | 31 ++++++++-----------------------
2 files changed, 8 insertions(+), 48 deletions(-)
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1708,31 +1708,6 @@ void fpsimd_signal_preserve_current_stat
}
/*
- * Called by KVM when entering the guest.
- */
-void fpsimd_kvm_prepare(void)
-{
- if (!system_supports_sve())
- return;
-
- /*
- * KVM does not save host SVE state since we can only enter
- * the guest from a syscall so the ABI means that only the
- * non-saved SVE state needs to be saved. If we have left
- * SVE enabled for performance reasons then update the task
- * state to be FPSIMD only.
- */
- get_cpu_fpsimd_context();
-
- if (test_and_clear_thread_flag(TIF_SVE)) {
- sve_to_fpsimd(current);
- current->thread.fp_type = FP_STATE_FPSIMD;
- }
-
- put_cpu_fpsimd_context();
-}
-
-/*
* Associate current's FPSIMD context with this cpu
* The caller must have ownership of the cpu FPSIMD context before calling
* this function.
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -79,14 +79,16 @@ void kvm_arch_vcpu_load_fp(struct kvm_vc
if (!system_supports_fpsimd())
return;
- fpsimd_kvm_prepare();
-
/*
- * We will check TIF_FOREIGN_FPSTATE just before entering the
- * guest in kvm_arch_vcpu_ctxflush_fp() and override this to
- * FP_STATE_FREE if the flag set.
+ * Ensure that any host FPSIMD/SVE/SME state is saved and unbound such
+ * that the host kernel is responsible for restoring this state upon
+ * return to userspace, and the hyp code doesn't need to save anything.
+ *
+ * When the host may use SME, fpsimd_save_and_flush_cpu_state() ensures
+ * that PSTATE.{SM,ZA} == {0,0}.
*/
- vcpu->arch.fp_state = FP_STATE_HOST_OWNED;
+ fpsimd_save_and_flush_cpu_state();
+ vcpu->arch.fp_state = FP_STATE_FREE;
vcpu_clear_flag(vcpu, HOST_SVE_ENABLED);
if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN)
@@ -96,23 +98,6 @@ void kvm_arch_vcpu_load_fp(struct kvm_vc
vcpu_clear_flag(vcpu, HOST_SME_ENABLED);
if (read_sysreg(cpacr_el1) & CPACR_EL1_SMEN_EL0EN)
vcpu_set_flag(vcpu, HOST_SME_ENABLED);
-
- /*
- * If PSTATE.SM is enabled then save any pending FP
- * state and disable PSTATE.SM. If we leave PSTATE.SM
- * enabled and the guest does not enable SME via
- * CPACR_EL1.SMEN then operations that should be valid
- * may generate SME traps from EL1 to EL1 which we
- * can't intercept and which would confuse the guest.
- *
- * Do the same for PSTATE.ZA in the case where there
- * is state in the registers which has not already
- * been saved, this is very unlikely to happen.
- */
- if (read_sysreg_s(SYS_SVCR) & (SVCR_SM_MASK | SVCR_ZA_MASK)) {
- vcpu->arch.fp_state = FP_STATE_FREE;
- fpsimd_save_and_flush_cpu_state();
- }
}
}
Patches currently in stable-queue which might be from broonie@kernel.org are
queue-6.6/kvm-arm64-calculate-cptr_el2-traps-on-activating-traps.patch
queue-6.6/regulator-check-that-dummy-regulator-has-been-probed-before-using-it.patch
queue-6.6/kvm-arm64-eagerly-switch-zcr_el-1-2.patch
queue-6.6/kvm-arm64-mark-some-header-functions-as-inline.patch
queue-6.6/kvm-arm64-remove-host-fpsimd-saving-for-non-protected-kvm.patch
queue-6.6/regulator-dummy-force-synchronous-probing.patch
queue-6.6/kvm-arm64-refactor-exit-handlers.patch
queue-6.6/kvm-arm64-unconditionally-save-flush-host-fpsimd-sve-sme-state.patch
queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.smen.patch
queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.zen.patch
^ permalink raw reply [flat|nested] 17+ messages in thread
* Patch "KVM: arm64: Mark some header functions as inline" has been added to the 6.6-stable tree
2025-03-21 0:16 ` [PATCH 6.6 7/8] KVM: arm64: Mark some header functions as inline Mark Brown
@ 2025-03-25 11:28 ` gregkh
0 siblings, 0 replies; 17+ messages in thread
From: gregkh @ 2025-03-25 11:28 UTC (permalink / raw)
To: broonie, catalin.marinas, gregkh, james.morse, kvmarm,
linux-arm-kernel, mark.rutland, maz, oliver.upton, suzuki.poulose,
tabba, will
Cc: stable-commits
This is a note to let you know that I've just added the patch titled
KVM: arm64: Mark some header functions as inline
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-arm64-mark-some-header-functions-as-inline.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
From broonie@kernel.org Thu Mar 20 20:18:37 2025
From: Mark Brown <broonie@kernel.org>
Date: Fri, 21 Mar 2025 00:16:07 +0000
Subject: KVM: arm64: Mark some header functions as inline
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 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>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Mark Brown <broonie@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Fuad Tabba <tabba@google.com>
Message-ID: <20250321-stable-sve-6-6-v1-7-0b3a6a14ea53@kernel.org>
From: Mark Rutland <mark.rutland@arm.com>
[ Upstream commit f9dd00de1e53a47763dfad601635d18542c3836d ]
The shared hyp switch header has a number of static functions which
might not be used by all files that include the header, and when unused
they will provoke compiler warnings, e.g.
| In file included from arch/arm64/kvm/hyp/nvhe/hyp-main.c:8:
| ./arch/arm64/kvm/hyp/include/hyp/switch.h:703:13: warning: 'kvm_hyp_handle_dabt_low' defined but not used [-Wunused-function]
| 703 | static bool kvm_hyp_handle_dabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
| | ^~~~~~~~~~~~~~~~~~~~~~~
| ./arch/arm64/kvm/hyp/include/hyp/switch.h:682:13: warning: 'kvm_hyp_handle_cp15_32' defined but not used [-Wunused-function]
| 682 | static bool kvm_hyp_handle_cp15_32(struct kvm_vcpu *vcpu, u64 *exit_code)
| | ^~~~~~~~~~~~~~~~~~~~~~
| ./arch/arm64/kvm/hyp/include/hyp/switch.h:662:13: warning: 'kvm_hyp_handle_sysreg' defined but not used [-Wunused-function]
| 662 | static bool kvm_hyp_handle_sysreg(struct kvm_vcpu *vcpu, u64 *exit_code)
| | ^~~~~~~~~~~~~~~~~~~~~
| ./arch/arm64/kvm/hyp/include/hyp/switch.h:458:13: warning: 'kvm_hyp_handle_fpsimd' defined but not used [-Wunused-function]
| 458 | static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
| | ^~~~~~~~~~~~~~~~~~~~~
| ./arch/arm64/kvm/hyp/include/hyp/switch.h:329:13: warning: 'kvm_hyp_handle_mops' defined but not used [-Wunused-function]
| 329 | static bool kvm_hyp_handle_mops(struct kvm_vcpu *vcpu, u64 *exit_code)
| | ^~~~~~~~~~~~~~~~~~~
Mark these functions as 'inline' to suppress this warning. This
shouldn't result in any functional change.
At the same time, avoid the use of __alias() in the header and alias
kvm_hyp_handle_iabt_low() and kvm_hyp_handle_watchpt_low() to
kvm_hyp_handle_memory_fault() using CPP, matching the style in the rest
of the kernel. For consistency, kvm_hyp_handle_memory_fault() is also
marked as 'inline'.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-8-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/kvm/hyp/include/hyp/switch.h | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -279,7 +279,7 @@ static inline void __hyp_sve_restore_gue
* If FP/SIMD is not implemented, handle the trap and inject an undefined
* instruction exception to the guest. Similarly for trapped SVE accesses.
*/
-static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
+static inline bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
{
bool sve_guest;
u8 esr_ec;
@@ -518,7 +518,7 @@ static bool handle_ampere1_tcr(struct kv
return true;
}
-static bool kvm_hyp_handle_sysreg(struct kvm_vcpu *vcpu, u64 *exit_code)
+static inline bool kvm_hyp_handle_sysreg(struct kvm_vcpu *vcpu, u64 *exit_code)
{
if (cpus_have_final_cap(ARM64_WORKAROUND_CAVIUM_TX2_219_TVM) &&
handle_tx2_tvm(vcpu))
@@ -541,7 +541,7 @@ static bool kvm_hyp_handle_sysreg(struct
return false;
}
-static bool kvm_hyp_handle_cp15_32(struct kvm_vcpu *vcpu, u64 *exit_code)
+static inline bool kvm_hyp_handle_cp15_32(struct kvm_vcpu *vcpu, u64 *exit_code)
{
if (static_branch_unlikely(&vgic_v3_cpuif_trap) &&
__vgic_v3_perform_cpuif_access(vcpu) == 1)
@@ -550,19 +550,18 @@ static bool kvm_hyp_handle_cp15_32(struc
return false;
}
-static bool kvm_hyp_handle_memory_fault(struct kvm_vcpu *vcpu, u64 *exit_code)
+static inline bool kvm_hyp_handle_memory_fault(struct kvm_vcpu *vcpu,
+ u64 *exit_code)
{
if (!__populate_fault_info(vcpu))
return true;
return false;
}
-static bool kvm_hyp_handle_iabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
- __alias(kvm_hyp_handle_memory_fault);
-static bool kvm_hyp_handle_watchpt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
- __alias(kvm_hyp_handle_memory_fault);
+#define kvm_hyp_handle_iabt_low kvm_hyp_handle_memory_fault
+#define kvm_hyp_handle_watchpt_low kvm_hyp_handle_memory_fault
-static bool kvm_hyp_handle_dabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
+static inline bool kvm_hyp_handle_dabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
{
if (kvm_hyp_handle_memory_fault(vcpu, exit_code))
return true;
Patches currently in stable-queue which might be from broonie@kernel.org are
queue-6.6/kvm-arm64-calculate-cptr_el2-traps-on-activating-traps.patch
queue-6.6/regulator-check-that-dummy-regulator-has-been-probed-before-using-it.patch
queue-6.6/kvm-arm64-eagerly-switch-zcr_el-1-2.patch
queue-6.6/kvm-arm64-mark-some-header-functions-as-inline.patch
queue-6.6/kvm-arm64-remove-host-fpsimd-saving-for-non-protected-kvm.patch
queue-6.6/regulator-dummy-force-synchronous-probing.patch
queue-6.6/kvm-arm64-refactor-exit-handlers.patch
queue-6.6/kvm-arm64-unconditionally-save-flush-host-fpsimd-sve-sme-state.patch
queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.smen.patch
queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.zen.patch
^ permalink raw reply [flat|nested] 17+ messages in thread
end of thread, other threads:[~2025-03-25 11:44 UTC | newest]
Thread overview: 17+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-03-21 0:16 [PATCH 6.6 0/8] KVM: arm64: Backport of SVE fixes to v6.6 Mark Brown
2025-03-21 0:16 ` [PATCH 6.6 1/8] KVM: arm64: Calculate cptr_el2 traps on activating traps Mark Brown
2025-03-25 11:28 ` Patch "KVM: arm64: Calculate cptr_el2 traps on activating traps" has been added to the 6.6-stable tree gregkh
2025-03-21 0:16 ` [PATCH 6.6 2/8] KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state Mark Brown
2025-03-25 11:28 ` Patch "KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state" has been added to the 6.6-stable tree gregkh
2025-03-21 0:16 ` [PATCH 6.6 3/8] KVM: arm64: Remove host FPSIMD saving for non-protected KVM Mark Brown
2025-03-25 11:28 ` Patch "KVM: arm64: Remove host FPSIMD saving for non-protected KVM" has been added to the 6.6-stable tree gregkh
2025-03-21 0:16 ` [PATCH 6.6 4/8] KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN Mark Brown
2025-03-25 11:28 ` Patch "KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN" has been added to the 6.6-stable tree gregkh
2025-03-21 0:16 ` [PATCH 6.6 5/8] KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN Mark Brown
2025-03-25 11:28 ` Patch "KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN" has been added to the 6.6-stable tree gregkh
2025-03-21 0:16 ` [PATCH 6.6 6/8] KVM: arm64: Refactor exit handlers Mark Brown
2025-03-25 11:28 ` Patch "KVM: arm64: Refactor exit handlers" has been added to the 6.6-stable tree gregkh
2025-03-21 0:16 ` [PATCH 6.6 7/8] KVM: arm64: Mark some header functions as inline Mark Brown
2025-03-25 11:28 ` Patch "KVM: arm64: Mark some header functions as inline" has been added to the 6.6-stable tree gregkh
2025-03-21 0:16 ` [PATCH 6.6 8/8] KVM: arm64: Eagerly switch ZCR_EL{1,2} Mark Brown
2025-03-25 11:28 ` Patch "KVM: arm64: Eagerly switch ZCR_EL{1,2}" has been added to the 6.6-stable tree gregkh
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