Re: [PATCH v3 10/12] KVM: arm64: nVHE: Support CONFIG_CFI_CLANG at EL2
From: Will Deacon <will@kernel.org>
Date: 2024-06-03 13:09:51
Also in:
kvm, kvmarm
On Wed, May 29, 2024 at 01:30:15PM +0100, Pierre-Clément Tosi wrote:
On Mon, May 13, 2024 at 06:30:05PM +0100, Will Deacon wrote:quoted
On Fri, May 10, 2024 at 12:26:39PM +0100, Pierre-Clément Tosi wrote:quoted
[...] Use SYM_TYPED_FUNC_START() for __pkvm_init_switch_pgd, as nVHE can't call it directly and must use a PA function pointer from C (because it is part of the idmap page), which would trigger a kCFI failure if the type ID wasn't present. Signed-off-by: Pierre-Clément Tosi <redacted> --- arch/arm64/include/asm/esr.h | 6 ++++++ arch/arm64/kvm/handle_exit.c | 11 +++++++++++ arch/arm64/kvm/hyp/nvhe/Makefile | 6 +++--- arch/arm64/kvm/hyp/nvhe/hyp-init.S | 6 +++++- 4 files changed, 25 insertions(+), 4 deletions(-) [...]diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S index 5a15737b4233..33fb5732ab83 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S +++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S@@ -5,6 +5,7 @@ */ #include <linux/arm-smccc.h> +#include <linux/cfi_types.h> #include <linux/linkage.h> #include <asm/alternative.h>@@ -268,8 +269,11 @@ SYM_CODE_END(__kvm_handle_stub_hvc) /* * void __pkvm_init_switch_pgd(struct kvm_nvhe_init_params *params, * void (*finalize_fn)(void)); + * + * SYM_TYPED_FUNC_START() allows C to call this ID-mapped function indirectly + * using a physical pointer without triggering a kCFI failure. */ -SYM_FUNC_START(__pkvm_init_switch_pgd) +SYM_TYPED_FUNC_START(__pkvm_init_switch_pgd) /* Load the inputs from the VA pointer before turning the MMU off */ ldr x5, [x0, #NVHE_INIT_PGD_PA] ldr x0, [x0, #NVHE_INIT_STACK_HYP_VA]Unrelated hunk?No, this is needed to prevent a kCFI failure at EL2. Please let me know if the comment and commit message aren't clear enough.
I'm not disputing that this hunk is needed, but I think it should be in place before the patch enabling CFI. For example, by merging it in with patch 2? Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel