Hi Quentin,
On 2021-01-08 12:15, Quentin Perret wrote:
Introduce the infrastructure in KVM enabling to copy CPU feature
registers into EL2-owned data-structures, to allow reading sanitised
values directly at EL2 in nVHE.
Given that only a subset of these features are being read by the
hypervisor, the ones that need to be copied are to be listed under
<asm/kvm_cpufeature.h> together with the name of the nVHE variable that
will hold the copy.
While at it, introduce the first user of this infrastructure by
implementing __flush_dcache_area at EL2, which needs
arm64_ftr_reg_ctrel0.
Signed-off-by: Quentin Perret <qperret@xxxxxxxxxx>
---
arch/arm64/include/asm/cpufeature.h | 1 +
arch/arm64/include/asm/kvm_cpufeature.h | 17 ++++++++++++++
arch/arm64/kernel/cpufeature.c | 12 ++++++++++
arch/arm64/kvm/arm.c | 31 +++++++++++++++++++++++++
arch/arm64/kvm/hyp/nvhe/Makefile | 3 ++-
arch/arm64/kvm/hyp/nvhe/cache.S | 13 +++++++++++
arch/arm64/kvm/hyp/nvhe/cpufeature.c | 8 +++++++
7 files changed, 84 insertions(+), 1 deletion(-)
create mode 100644 arch/arm64/include/asm/kvm_cpufeature.h
create mode 100644 arch/arm64/kvm/hyp/nvhe/cache.S
create mode 100644 arch/arm64/kvm/hyp/nvhe/cpufeature.c
diff --git a/arch/arm64/include/asm/cpufeature.h
b/arch/arm64/include/asm/cpufeature.h
index 16063c813dcd..742e9bcc051b 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -600,6 +600,7 @@ void __init setup_cpu_features(void);
void check_local_cpu_capabilities(void);
u64 read_sanitised_ftr_reg(u32 id);
+int copy_ftr_reg(u32 id, struct arm64_ftr_reg *dst);
static inline bool cpu_supports_mixed_endian_el0(void)
{
diff --git a/arch/arm64/include/asm/kvm_cpufeature.h
b/arch/arm64/include/asm/kvm_cpufeature.h
new file mode 100644
index 000000000000..d34f85cba358
--- /dev/null
+++ b/arch/arm64/include/asm/kvm_cpufeature.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020 - Google LLC
+ * Author: Quentin Perret <qperret@xxxxxxxxxx>
+ */
+
+#include <asm/cpufeature.h>
+
+#ifndef KVM_HYP_CPU_FTR_REG
+#if defined(__KVM_NVHE_HYPERVISOR__)
+#define KVM_HYP_CPU_FTR_REG(id, name) extern struct arm64_ftr_reg
name;
+#else
+#define KVM_HYP_CPU_FTR_REG(id, name) DECLARE_KVM_NVHE_SYM(name);
+#endif
+#endif
+
+KVM_HYP_CPU_FTR_REG(SYS_CTR_EL0, arm64_ftr_reg_ctrel0)
diff --git a/arch/arm64/kernel/cpufeature.c
b/arch/arm64/kernel/cpufeature.c
index bc3549663957..c2019aaaadc3 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1113,6 +1113,18 @@ u64 read_sanitised_ftr_reg(u32 id)
}
EXPORT_SYMBOL_GPL(read_sanitised_ftr_reg);
+int copy_ftr_reg(u32 id, struct arm64_ftr_reg *dst)
+{
+ struct arm64_ftr_reg *regp = get_arm64_ftr_reg(id);
+
+ if (!regp)
+ return -EINVAL;
+
+ memcpy(dst, regp, sizeof(*regp));
+
+ return 0;
+}
+
#define read_sysreg_case(r) \
case r: return read_sysreg_s(r)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 51b53ca36dc5..9fd769349e9e 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -34,6 +34,7 @@
#include <asm/virt.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_asm.h>
+#include <asm/kvm_cpufeature.h>
#include <asm/kvm_mmu.h>
#include <asm/kvm_emulate.h>
#include <asm/sections.h>
@@ -1697,6 +1698,29 @@ static void teardown_hyp_mode(void)
}
}
+#undef KVM_HYP_CPU_FTR_REG
+#define KVM_HYP_CPU_FTR_REG(id, name) \
+ { .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) },
+static const struct __ftr_reg_copy_entry {
+ u32 sys_id;
+ struct arm64_ftr_reg *dst;
Why do we need the whole data structure? Can't we just live with
sys_val?
+} hyp_ftr_regs[] = {
+ #include <asm/kvm_cpufeature.h>
+};
Can't this be made __initdata?
+
+static int copy_cpu_ftr_regs(void)
+{
+ int i, ret;
+
+ for (i = 0; i < ARRAY_SIZE(hyp_ftr_regs); i++) {
+ ret = copy_ftr_reg(hyp_ftr_regs[i].sys_id, hyp_ftr_regs[i].dst);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
/**
* Inits Hyp-mode on all online CPUs
*/
@@ -1705,6 +1729,13 @@ static int init_hyp_mode(void)
int cpu;
int err = 0;
+ /*
+ * Copy the required CPU feature register in their EL2 counterpart
+ */
+ err = copy_cpu_ftr_regs();
+ if (err)
+ return err;
+
Just to keep things together, please move any sysreg manipulation into
sys_regs.c, most probably into kvm_sys_reg_table_init().
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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