[PATCH v7 16/27] KVM: arm64: Factor out core register ID enumeration

Dave Martin
2019-03-29T13:18:53Z

In preparation for adding logic to filter out some KVM_REG_ARM_CORE
registers from the KVM_GET_REG_LIST output, this patch factors out
the core register enumeration into a separate function and rebuilds
num_core_regs() on top of it.

This may be a little more expensive (depending on how good a job
the compiler does of specialising the code), but KVM_GET_REG_LIST
is not a hot path.

This will make it easier to consolidate ID filtering code in one
place.

No functional change.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com>

---

Changes since v5:

* New patch.

This reimplements part of the separately-posted patch "KVM: arm64:
Factor out KVM_GET_REG_LIST core register enumeration", minus aspects
that potentially break the ABI.

As a result, the opportunity to truly consolidate all the ID reg
filtering in one place is deliberately left on the floor, for now.
This will be addressed in a separate series later on.
---
arch/arm64/kvm/guest.c | 33 +++++++++++++++++++++++++--------
1 file changed, 25 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 3e38eb2..a391a61 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -23,6 +23,7 @@
#include <linux/err.h>
#include <linux/kvm_host.h>
#include <linux/module.h>
+#include <linux/stddef.h>
#include <linux/string.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
@@ -194,9 +195,28 @@ int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
return -EINVAL;
}

+static int kvm_arm_copy_core_reg_indices(u64 __user *uindices)
+{
+ unsigned int i;
+ int n = 0;
+ const u64 core_reg = KVM_REG_ARM64 | KVM_REG_SIZE_U64 | KVM_REG_ARM_CORE;
+
+ for (i = 0; i < sizeof(struct kvm_regs) / sizeof(__u32); i++) {
+ if (uindices) {
+ if (put_user(core_reg | i, uindices))
+ return -EFAULT;
+ uindices++;
+ }
+
+ n++;
+ }
+
+ return n;
+}
+
static unsigned long num_core_regs(void)
{
- return sizeof(struct kvm_regs) / sizeof(__u32);
+ return kvm_arm_copy_core_reg_indices(NULL);
}

/**
@@ -276,15 +296,12 @@ unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu)
*/
int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
{
- unsigned int i;
- const u64 core_reg = KVM_REG_ARM64 | KVM_REG_SIZE_U64 | KVM_REG_ARM_CORE;
int ret;

- for (i = 0; i < sizeof(struct kvm_regs) / sizeof(__u32); i++) {
- if (put_user(core_reg | i, uindices))
- return -EFAULT;
- uindices++;
- }
+ ret = kvm_arm_copy_core_reg_indices(uindices);
+ if (ret)
+ return ret;
+ uindices += ret;

ret = kvm_arm_copy_fw_reg_indices(vcpu, uindices);
if (ret)
--
2.1.4