In struct vcpu_arch, the debug_flags field is used to store
debug-related flags about the vcpu state.
Since we are about to add some more flags related to FPSIMD and
SVE, it makes sense to add them to the existing flags field rather
than adding new fields. Since there is only one debug_flags flag
defined so far, there is plenty of free space for expansion.
In preparation for adding more flags, this patch renames the
debug_flags field to simply "flags", and updates comments
appropriately.
The flag definitions are also moved to <asm/kvm_host.h>, since
their presence in <asm/kvm_asm.h> was for purely historical
reasons: these definitions are not used from asm any more, and not
very likely to be as more Hyp asm is migrated to C.
KVM_ARM64_DEBUG_DIRTY_SHIFT has not been used since commit
1ea66d27e7 ("arm64: KVM: Move away from the assembly version of
the world switch"), so this patch gets rid of that too.
No functional change.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
[maz: fixed minor conflict]
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Currently we access the system registers array via the vcpu_sys_reg()
macro. However, we are about to change the behavior to some times
modify the register file directly, so let's change this to two
primitives:
* Accessor macros vcpu_write_sys_reg() and vcpu_read_sys_reg()
* Direct array access macro __vcpu_sys_reg()
The accessor macros should be used in places where the code needs to
access the currently loaded VCPU's state as observed by the guest. For
example, when trapping on cache related registers, a write to a system
register should go directly to the VCPU version of the register.
The direct array access macro can be used in places where the VCPU is
known to never be running (for example userspace access) or for
registers which are never context switched (for example all the PMU
system registers).
This rewrites all users of vcpu_sys_regs to one of the macros described
above.
No functional change.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Christoffer Dall <cdall@cs.columbia.edu>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
There is no need to figure out inside the world-switch if we should
save/restore the debug registers or not, we might as well do that in the
higher level debug setup code, making it easier to optimize down the
line.
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
After emulating instructions we may want return to user-space to handle
single-step debugging. Introduce a helper function, which, if
single-step is enabled, sets the run structure for return and returns
true.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
The SPE buffer is virtually addressed, using the page tables of the CPU
MMU. Unusually, this means that the EL0/1 page table may be live whilst
we're executing at EL2 on non-VHE configurations. When VHE is in use,
we can use the same property to profile the guest behind its back.
This patch adds the relevant disabling and flushing code to KVM so that
the host can make use of SPE without corrupting guest memory, and any
attempts by a guest to use SPE will result in a trap.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Alex Bennée <alex.bennee@linaro.org>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This includes trace points for:
kvm_arch_setup_guest_debug
kvm_arch_clear_guest_debug
I've also added some generic register setting trace events and also a
trace point to dump the array of hardware registers.
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Finally advertise the KVM capability for SET_GUEST_DEBUG. Once arm
support is added this check can be moved to the common
kvm_vm_ioctl_check_extension() code.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This introduces a level of indirection for the debug registers. Instead
of using the sys_regs[] directly we store registers in a structure in
the vcpu. The new kvm_arm_reset_debug_ptr() sets the debug ptr to the
guest context.
Because we no longer give the sys_regs offset for the sys_reg_desc->reg
field, but instead the index into a debug-specific struct we need to
add a number of additional trap functions for each register. Also as the
generic generic user-space access code no longer works we have
introduced a new pair of function pointers to the sys_reg_desc structure
to override the generic code when needed.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This adds support for single-stepping the guest. To do this we need to
manipulate the guests PSTATE.SS and MDSCR_EL1.SS bits to trigger
stepping. We take care to preserve MDSCR_EL1 and trap access to it to
ensure we don't affect the apparent state of the guest.
As we have to enable trapping of all software debug exceptions we
suppress the ability of the guest to single-step itself. If we didn't we
would have to deal with the exception arriving while the guest was in
kernelspace when the guest is expecting to single-step userspace. This
is something we don't want to unwind in the kernel. Once the host is no
longer debugging the guest its ability to single-step userspace is
restored.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This adds support for SW breakpoints inserted by userspace.
We do this by trapping all guest software debug exceptions to the
hypervisor (MDCR_EL2.TDE). The exit handler sets an exit reason of
KVM_EXIT_DEBUG with the kvm_debug_exit_arch structure holding the
exception syndrome information.
It will be up to userspace to extract the PC (via GET_ONE_REG) and
determine if the debug event was for a breakpoint it inserted. If not
userspace will need to re-inject the correct exception restart the
hypervisor to deliver the debug exception to the guest.
Any other guest software debug exception (e.g. single step or HW
assisted breakpoints) will cause an error and the VM to be killed. This
is addressed by later patches which add support for the other debug
types.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This is a precursor for later patches which will need to do more to
setup debug state before entering the hyp.S switch code. The existing
functionality for setting mdcr_el2 has been moved out of hyp.S and now
uses the value kept in vcpu->arch.mdcr_el2.
As the assembler used to previously mask and preserve MDCR_EL2.HPMN I've
had to add a mechanism to save the value of mdcr_el2 as a per-cpu
variable during the initialisation code. The kernel never sets this
number so we are assuming the bootcode has set up the correct value
here.
This also moves the conditional setting of the TDA bit from the hyp code
into the C code which is currently used for the lazy debug register
context switch code.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
