On 28/07/2016 21:36, Tamas K Lengyel wrote:
On Thu, Jul 28, 2016 at 2:26 PM, Andrew Cooper
<andrew.coop...@citrix.com> wrote:
On 28/07/2016 21:05, Tamas K Lengyel wrote:
Add support for getting/setting registers through vm_event on ARM.
The set of registers can be expanded in the future to include other registers
as well if necessary but for now it is limited to TTB/CR/R0/R1, PC and CPSR.
Signed-off-by: Tamas K Lengyel <tamas.leng...@zentific.com>
---
Cc: Stefano Stabellini <sstabell...@kernel.org>
Cc: Julien Grall <julien.gr...@arm.com>
Cc: Razvan Cojocaru <rcojoc...@bitdefender.com>
Cc: Jan Beulich <jbeul...@suse.com>
Cc: Andrew Cooper <andrew.coop...@citrix.com>
For the x86 and common bits, Reviewed-by: Andrew Cooper
<andrew.coop...@citrix.com>
However,
+#include <xen/sched.h>
+#include <asm/vm_event.h>
+
+void vm_event_fill_regs(vm_event_request_t *req)
+{
+ const struct cpu_user_regs *regs = guest_cpu_user_regs();
+
+ req->data.regs.arm.cpsr = regs->cpsr;
+ req->data.regs.arm.pc = regs->pc;
+ req->data.regs.arm.ttbcr = READ_SYSREG(TCR_EL1);
+ req->data.regs.arm.ttbr0 = READ_SYSREG64(TTBR0_EL1);
+ req->data.regs.arm.ttbr1 = READ_SYSREG64(TTBR1_EL1);
+}
+
+void vm_event_set_registers(struct vcpu *v, vm_event_response_t *rsp)
+{
+ struct cpu_user_regs *regs = guest_cpu_user_regs();
+
+ regs->cpsr = rsp->data.regs.arm.cpsr;
+ regs->pc = rsp->data.regs.arm.pc;
+ v->arch.ttbcr = rsp->data.regs.arm.ttbcr;
+ v->arch.ttbr0 = rsp->data.regs.arm.ttbr0;
+ v->arch.ttbr1 = rsp->data.regs.arm.ttbr1;
Not knowing anything about ARM, but this looks like it is missing some
sanity/plausibility checks (to protect Xen against accidental clobbering
from the vm_event listener), and some WRITE_SYSREG() to reload the new
values (unless this is done unconditionally later, at which point you
should at least leave a comment here saying so).
This function only ever gets called if the vm_event response
specifically has the VM_EVENT_FLAG_SET_REGISTERS set, so accidental
clobbering is not possible. Also, using WRITE_SYSREG() is not safe at
this point because current != v. However, I have another issue here
with regs which should actually be:
What if the vCPU is running? If it cannot happen, please document and
add an ASSERT/BUG_ON.
struct cpu_user_regs *regs = &v->arch.cpu_info->guest_cpu_user_regs;
I'll fix that shortly.
Thanks,
Tamas
--
Julien Grall
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