Hardware debugging in guests is not intercepted currently, it means
that a malicious guest can bring down the entire machine by writing
to the debug registers.
This patch enable trapping of all debug registers, preventing the
guests to access the debug registers. This includes access to the
debug mode(DBGDSCR) in the guest world all the time which could
otherwise mess with the host state. Reads return 0 and writes are
ignored (RAZ_WI).
The result is the guest cannot detect any working hardware based debug
support. As debug exceptions are still routed to the guest normal
debug using software based breakpoints still works.
To support debugging using hardware registers we need to implement a
debug register aware world switch as well as special trapping for
registers that may affect the host state.
Cc: stable@vger.kernel.org
Signed-off-by: Zhichao Huang <zhichao.huang@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
We like living dangerously. Nothing explicitely forbids stack-protector
to be used in the HYP code, while distributions routinely compile their
kernel with it. We're just lucky that no code actually triggers the
instrumentation.
Let's not try our luck for much longer, and disable stack-protector
for code living at HYP.
Cc: stable@vger.kernel.org
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
When entering the hyp stub implemented in the idmap, we try to
be mindful of the fact that we could be running a Thumb-2 kernel
by adding 1 to the address we compute. Unfortunately, the assembler
also knows about this trick, and has already generated an address
that has bit 0 set in the litteral pool.
Our superfluous correction ends up confusing the CPU entierely,
as we now branch to the stub in ARM mode instead of Thumb, and on
a possibly unaligned address for good measure. From that point,
nothing really good happens.
The obvious fix in to remove this stupid target PC correction.
Fixes: 6bebcecb6c ("ARM: KVM: Allow the main HYP code to use the init hyp stub implementation")
Reported-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
We now have a full hyp-stub implementation in the KVM init code,
but the main KVM code only supports HVC_GET_VECTORS, which is not
enough.
Instead of reinventing the wheel, let's reuse the init implementation
by branching to the idmap page when called with a hyp-stub hypercall.
Tested-by: Keerthy <j-keerthy@ti.com>
Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
The conversion of the HYP stub ABI to something similar to arm64
left the KVM code broken, as it doesn't know about the new
stub numbering. Let's move the various #defines to virt.h, and
let KVM use HVC_GET_VECTORS.
Tested-by: Keerthy <j-keerthy@ti.com>
Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
Architecturally, TLBs are private to the (physical) CPU they're
associated with. But when multiple vcpus from the same VM are
being multiplexed on the same CPU, the TLBs are not private
to the vcpus (and are actually shared across the VMID).
Let's consider the following scenario:
- vcpu-0 maps PA to VA
- vcpu-1 maps PA' to VA
If run on the same physical CPU, vcpu-1 can hit TLB entries generated
by vcpu-0 accesses, and access the wrong physical page.
The solution to this is to keep a per-VM map of which vcpu ran last
on each given physical CPU, and invalidate local TLBs when switching
to a different vcpu from the same VM.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This patch allows to build and use vgic-v3 in 32-bit mode.
Unfortunately, it can not be split in several steps without extra
stubs to keep patches independent and bisectable. For instance,
virt/kvm/arm/vgic/vgic-v3.c uses function from vgic-v3-sr.c, handling
access to GICv3 cpu interface from the guest requires vgic_v3.vgic_sre
to be already defined.
It is how support has been done:
* handle SGI requests from the guest
* report configured SRE on access to GICv3 cpu interface from the guest
* required vgic-v3 macros are provided via uapi.h
* static keys are used to select GIC backend
* to make vgic-v3 build KVM_ARM_VGIC_V3 guard is removed along with
the static inlines
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Just like for arm64, we can handle asynchronous aborts being
delivered at HYP while being caused by the guest. We use
the exact same method to catch such an abort, and soldier on.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
The HCR.VA bit is used to signal an Abort to a guest, and has
the peculiar feature of getting cleared when the guest has taken
the abort (this is the only bit that behaves as such in this register).
This means that if we signal such an abort, we must leave it in
the guest context until it disappears from HCR, and at which point
it must be cleared from the context.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
When rewriting the assembly code to C code, it was useful to have
exported aliases or static functions so that we could keep the existing
common C code unmodified and at the same time rewrite arm64 from
assembly to C code, and later do the arm part.
Now when both are done, we really don't need this level of indirection
anymore, and it's time to save a few lines and brain cells.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Using the common HYP timer code is a bit more tricky, since we
use system register names. Nothing a set of macros cannot
work around...
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
No need to keep our own private version, the common one is
strictly identical.
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
In order to be able to use the code located in virt/kvm/arm/hyp,
we need to make the global hyp.h file accessible from include/asm,
similar to what we did for arm64.
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Now that the old code is long gone, we can remove all the weak
attributes, as there is only one version of the code.
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
As we now have hooks to setup VTCR from C code, let's drop the
original VTCR setup and reimplement it as part of the HYP code.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Instead of spinning forever, let's "properly" handle any unexpected
exception ("properly" meaning "print a spat on the console and die").
This has proved useful quite a few times...
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This part is almost entierely borrowed from the existing code, just
slightly simplifying the HYP function call (as we now save SPSR_hyp
in the world switch).
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
On guest exit, we must take care of populating our fault data
structure so that the host code can handle it. This includes
resolving the IPA for permission faults, which can result in
restarting the guest.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
The new world switch implementation is modeled after the arm64 one,
calling the various save/restore functions in turn, and having as
little state as possible.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Similar to the arm64 version, add the code that deals with VFP traps,
re-enabling VFP, save/restoring the registers and resuming the guest.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Add the very minimal piece of code that is now required to jump
into the guest (and return from it). This code is only concerned
with save/restoring the USR registers (r0-r12+lr for the guest,
r4-r12+lr for the host), as everything else is dealt with in C
(VFP is another matter though).
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Banked registers are one of the many perks of the 32bit architecture,
and the world switch needs to cope with it.
This requires some "special" accessors, as these are not accessed
using a standard coprocessor instruction.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This is almost a copy/paste of the existing version, with a couple
of subtle differences:
- Only write to FPEXC once on the save path
- Add an isb when enabling VFP access
The patch also defines a few sysreg accessors and a __vfp_enabled
predicate that test the VFP trapping state.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This patch shouldn't exist, as we should be able to reuse the
arm64 version for free. I'll get there eventually, but in the
meantime I need an interrupt controller.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This patch shouldn't exist, as we should be able to reuse the
arm64 version for free. I'll get there eventually, but in the
meantime I need a timer ticking.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Concert the CP15 save/restore code to C.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
In order to move system register (CP15, mostly) access to C code,
add a few macros to facilitate this, and minimize the difference
between 32 and 64bit CP15 registers.
This will get heavily used in the following patches.
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
In order to expose the various HYP services that are private to
the hypervisor, add a new hyp.h file.
So far, it only contains mundane things such as section annotation
and VA manipulation.
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
