On 2020-05-26 17:29, James Morse wrote:

Hi Marc,

On 22/04/2020 13:00, Marc Zyngier wrote:

quoted

struct kvm_regs is used by userspace to indicate which register gets
accessed by the {GET,SET}_ONE_REG API. But as we're about to refactor
the layout of the in-kernel register structures, we need the kernel to
move away from it.

Let's make kvm_regs userspace only, and let the kernel map it to its 
own
internal representation.

quoted

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 23ebe51410f06..9fec9231b63e2 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c

@@ -102,6 +102,55 @@ static int core_reg_size_from_offset(const struct 

kvm_vcpu *vcpu, u64 off)
 	return size;
 }

+static void *core_reg_addr(struct kvm_vcpu *vcpu, const struct 
kvm_one_reg *reg)
+{
+	u64 off = core_reg_offset_from_id(reg->id);
+
+	switch (off) {

quoted

+	default:
+		return NULL;

Doesn't this switch statement catch an out of range offset, and a
misaligned offset?

... We still test for those explicitly in the caller. Better safe than 
implicit?

Indeed, this is not supposed to happen at all. Maybe I should just fold
validate_core_offset offset there, and make this NULL value the error
case.

quoted

+	}
+}

With the reset thing reported by Zenghui and Zengtao on the previous
patch fixed:
Reviewed-by: James Morse <james.morse@arm.com>

(otherwise struct kvm_regs isn't userspace-only!)

Indeed!

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...

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