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Message-Id: <20250314-stable-sve-6-12-v1-3-ddc16609d9ba@kernel.org>
Date: Fri, 14 Mar 2025 00:35:15 +0000
From: Mark Brown <broonie@...nel.org>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>,
Joey Gouly <joey.gouly@....com>, Suzuki K Poulose <suzuki.poulose@....com>,
Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
linux-kernel@...r.kernel.org, stable@...r.kernel.org,
Mark Brown <broonie@...nel.org>, Mark Rutland <mark.rutland@....com>,
Fuad Tabba <tabba@...gle.com>
Subject: [PATCH 6.12 3/8] KVM: arm64: Remove host FPSIMD saving for
non-protected KVM
From: Mark Rutland <mark.rutland@....com>
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@....com>
Reviewed-by: Mark Brown <broonie@...nel.org>
Tested-by: Mark Brown <broonie@...nel.org>
Acked-by: Will Deacon <will@...nel.org>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Fuad Tabba <tabba@...gle.com>
Cc: Marc Zyngier <maz@...nel.org>
Cc: Oliver Upton <oliver.upton@...ux.dev>
Reviewed-by: Oliver Upton <oliver.upton@...ux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-3-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@...nel.org>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
arch/arm64/include/asm/kvm_host.h | 20 +++++---------------
arch/arm64/kvm/arm.c | 8 --------
arch/arm64/kvm/fpsimd.c | 2 --
arch/arm64/kvm/hyp/include/hyp/switch.h | 25 +++++++++++++++++++++++--
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 2 +-
arch/arm64/kvm/hyp/nvhe/switch.c | 28 ----------------------------
arch/arm64/kvm/hyp/vhe/switch.c | 8 --------
7 files changed, 29 insertions(+), 64 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index d148cf578cb84e7dec4d1add2afa60a3c7a1e041..d8802490b25cba65369f03d94627a2624f14b072 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -602,23 +602,13 @@ struct kvm_host_data {
struct kvm_cpu_context host_ctxt;
/*
- * All pointers in this union are hyp VA.
+ * Hyp VA.
* sve_state is only used in pKVM and if system_supports_sve().
*/
- union {
- struct user_fpsimd_state *fpsimd_state;
- struct cpu_sve_state *sve_state;
- };
-
- union {
- /* HYP VA pointer to the host storage for FPMR */
- u64 *fpmr_ptr;
- /*
- * Used by pKVM only, as it needs to provide storage
- * for the host
- */
- u64 fpmr;
- };
+ struct cpu_sve_state *sve_state;
+
+ /* Used by pKVM only. */
+ u64 fpmr;
/* Ownership of the FP regs */
enum {
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index e6f0443210a8b7a65f616b25b2e6f74a05683ed6..634d3f62481827a3bf3aba6bf78cafed71b5bd32 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -2476,14 +2476,6 @@ static void finalize_init_hyp_mode(void)
per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->sve_state =
kern_hyp_va(sve_state);
}
- } else {
- for_each_possible_cpu(cpu) {
- struct user_fpsimd_state *fpsimd_state;
-
- fpsimd_state = &per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->host_ctxt.fp_regs;
- per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->fpsimd_state =
- kern_hyp_va(fpsimd_state);
- }
}
}
diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index efb54ed60fe1d1d8a904b10a4a4bd3c820d9dac5..2ee6bde85235581d6bc9cba7e578c55875b5d5a1 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -64,8 +64,6 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
*/
fpsimd_save_and_flush_cpu_state();
*host_data_ptr(fp_owner) = FP_STATE_FREE;
- *host_data_ptr(fpsimd_state) = NULL;
- *host_data_ptr(fpmr_ptr) = NULL;
vcpu_clear_flag(vcpu, HOST_SVE_ENABLED);
if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN)
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 5310fe1da6165bcdedfb5ce61bce353e4c9dd58b..a7f6a653f33718d1a25e232608e63ea287f2a672 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -344,7 +344,28 @@ static inline void __hyp_sve_save_host(void)
true);
}
-static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu);
+static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu)
+{
+ /*
+ * Non-protected kvm relies on the host restoring its sve state.
+ * Protected kvm restores the host's sve state as not to reveal that
+ * fpsimd was used by a guest nor leak upper sve bits.
+ */
+ if (system_supports_sve()) {
+ __hyp_sve_save_host();
+
+ /* Re-enable SVE traps if not supported for the guest vcpu. */
+ if (!vcpu_has_sve(vcpu))
+ cpacr_clear_set(CPACR_ELx_ZEN, 0);
+
+ } else {
+ __fpsimd_save_state(host_data_ptr(host_ctxt.fp_regs));
+ }
+
+ if (kvm_has_fpmr(kern_hyp_va(vcpu->kvm)))
+ *host_data_ptr(fpmr) = read_sysreg_s(SYS_FPMR);
+}
+
/*
* We trap the first access to the FP/SIMD to save the host context and
@@ -394,7 +415,7 @@ 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 (host_owns_fp_regs())
+ if (is_protected_kvm_enabled() && host_owns_fp_regs())
kvm_hyp_save_fpsimd_host(vcpu);
/* Restore the guest state */
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index fefc89209f9e41c95478f6770881eb314a38b4c2..4e757a77322c9efc59cdff501745f7c80d452358 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -83,7 +83,7 @@ static void fpsimd_sve_sync(struct kvm_vcpu *vcpu)
if (system_supports_sve())
__hyp_sve_restore_host();
else
- __fpsimd_restore_state(*host_data_ptr(fpsimd_state));
+ __fpsimd_restore_state(host_data_ptr(host_ctxt.fp_regs));
if (has_fpmr)
write_sysreg_s(*host_data_ptr(fpmr), SYS_FPMR);
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 81d933a71310fd1132b2450cd08108e071a2cf78..3ce16f90fe6af7be21bc7b84a9d8b3905b8b08a7 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -193,34 +193,6 @@ static bool kvm_handle_pvm_sys64(struct kvm_vcpu *vcpu, u64 *exit_code)
kvm_handle_pvm_sysreg(vcpu, exit_code));
}
-static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu)
-{
- /*
- * Non-protected kvm relies on the host restoring its sve state.
- * Protected kvm restores the host's sve state as not to reveal that
- * fpsimd was used by a guest nor leak upper sve bits.
- */
- if (unlikely(is_protected_kvm_enabled() && system_supports_sve())) {
- __hyp_sve_save_host();
-
- /* Re-enable SVE traps if not supported for the guest vcpu. */
- if (!vcpu_has_sve(vcpu))
- cpacr_clear_set(CPACR_ELx_ZEN, 0);
-
- } else {
- __fpsimd_save_state(*host_data_ptr(fpsimd_state));
- }
-
- if (kvm_has_fpmr(kern_hyp_va(vcpu->kvm))) {
- u64 val = read_sysreg_s(SYS_FPMR);
-
- if (unlikely(is_protected_kvm_enabled()))
- *host_data_ptr(fpmr) = val;
- else
- **host_data_ptr(fpmr_ptr) = val;
- }
-}
-
static const exit_handler_fn hyp_exit_handlers[] = {
[0 ... ESR_ELx_EC_MAX] = NULL,
[ESR_ELx_EC_CP15_32] = kvm_hyp_handle_cp15_32,
diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
index 80581b1c399595fd64d0ccada498edac322480a6..e7ca0424107adec2371ae4553ebab9857c60b6d9 100644
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -309,14 +309,6 @@ static bool kvm_hyp_handle_eret(struct kvm_vcpu *vcpu, u64 *exit_code)
return true;
}
-static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu)
-{
- __fpsimd_save_state(*host_data_ptr(fpsimd_state));
-
- if (kvm_has_fpmr(vcpu->kvm))
- **host_data_ptr(fpmr_ptr) = read_sysreg_s(SYS_FPMR);
-}
-
static bool kvm_hyp_handle_tlbi_el2(struct kvm_vcpu *vcpu, u64 *exit_code)
{
int ret = -EINVAL;
--
2.39.5
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