On 2019-10-21 11:21, Steven Price wrote:
On 19/10/2019 12:12, Marc Zyngier wrote:
On Fri, 11 Oct 2019 13:59:25 +0100,
Steven Price <steven.price@xxxxxxx> wrote:
Implement the service call for configuring a shared structure
between a
VCPU and the hypervisor in which the hypervisor can write the time
stolen from the VCPU's execution time by other tasks on the host.
User space allocates memory which is placed at an IPA also chosen
by user
space. The hypervisor then updates the shared structure using
kvm_put_guest() to ensure single copy atomicity of the 64-bit value
reporting the stolen time in nanoseconds.
Whenever stolen time is enabled by the guest, the stolen time
counter is
reset.
The stolen time itself is retrieved from the sched_info structure
maintained by the Linux scheduler code. We enable SCHEDSTATS when
selecting KVM Kconfig to ensure this value is meaningful.
Signed-off-by: Steven Price <steven.price@xxxxxxx>
---
arch/arm/include/asm/kvm_host.h | 20 +++++++++++
arch/arm64/include/asm/kvm_host.h | 21 +++++++++++-
arch/arm64/kvm/Kconfig | 1 +
include/linux/kvm_types.h | 2 ++
virt/kvm/arm/arm.c | 11 ++++++
virt/kvm/arm/hypercalls.c | 3 ++
virt/kvm/arm/pvtime.c | 56
+++++++++++++++++++++++++++++++
7 files changed, 113 insertions(+), 1 deletion(-)
[...]
+long kvm_hypercall_stolen_time(struct kvm_vcpu *vcpu)
Why long? If that's a base address, then it is either a phys_addr_t
or
a gpa_t. I'd suggest you move the error check to the caller.
This is a bit more tricky. It's a long because that's the declared
type
of the SMCCC return in kvm_hvc_call_handler(). I can't (easily) move
the
code into kvm_hvc_call_handler() because that is compiled for arm (as
well as arm64) and we don't have the definitions for stolen time
there.
The best option I could come up with is to have a dummy stub for arm
and
use generic types for this function.
This means we need a type which can contain both a gpa_t and the
SMCCC_RET_NOT_SUPPORTED error code.
I'm open to alternative suggestions on how to make this work.
My suggestion would be to always return a gpa_t from this function, and
change the 32bit stub for kvm_hypercall_stolen_time() to always return
GPA_INVALID.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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