Commit 6928bcc8 authored Jul 26, 2022 by Kalesh Singh Committed by Marc Zyngier Jul 26, 2022

KVM: arm64: Allocate shared pKVM hyp stacktrace buffers



In protected nVHE mode the host cannot directly access
hypervisor memory, so we will dump the hypervisor stacktrace
to a shared buffer with the host.

The minimum size for the buffer required, assuming the min frame
size of [x29, x30] (2 * sizeof(long)), is half the combined size of
the hypervisor and overflow stacks plus an additional entry to
delimit the end of the stacktrace.

The stacktrace buffers are used later in the series to dump the
nVHE hypervisor stacktrace when using protected-mode.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220726073750.3219117-14-kaleshsingh@google.com

parent 72adac1b

arch/arm64/include/asm/memory.h

+8 −0

Original line number	Diff line number	Diff line
		@@ -113,6 +113,14 @@

		#define OVERFLOW_STACK_SIZE SZ_4K

		/*
		* With the minimum frame size of [x29, x30], exactly half the combined
		* sizes of the hyp and overflow stacks is the maximum size needed to
		* save the unwinded stacktrace; plus an additional entry to delimit the
		* end.
		*/
		#define NVHE_STACKTRACE_SIZE ((OVERFLOW_STACK_SIZE + PAGE_SIZE) / 2 + sizeof(long))

		/*
		* Alignment of kernel segments (e.g. .text, .data).
		*

arch/arm64/kvm/hyp/nvhe/stacktrace.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -34,6 +34,10 @@ static void hyp_prepare_backtrace(unsigned long fp, unsigned long pc)
		stacktrace_info->pc = pc;
		}

		#ifdef CONFIG_PROTECTED_NVHE_STACKTRACE
		DEFINE_PER_CPU(unsigned long [NVHE_STACKTRACE_SIZE/sizeof(long)], pkvm_stacktrace);
		#endif /* CONFIG_PROTECTED_NVHE_STACKTRACE */

		/*
		* kvm_nvhe_prepare_backtrace - prepare to dump the nVHE backtrace
		*