From 56961c6331463cce2d84d0f973177a517fb33a82 Mon Sep 17 00:00:00 2001 From: Quentin Perret Date: Thu, 16 Jun 2022 16:11:34 +0000 Subject: [PATCH 1/2] KVM: arm64: Prevent kmemleak from accessing pKVM memory Commit a7259df76702 ("memblock: make memblock_find_in_range method private") changed the API using which memory is reserved for the pKVM hypervisor. However, memblock_phys_alloc() differs from the original API in terms of kmemleak semantics -- the old one didn't report the reserved regions to kmemleak while the new one does. Unfortunately, when protected KVM is enabled, all kernel accesses to pKVM-private memory result in a fatal exception, which can now happen because of kmemleak scans: $ echo scan > /sys/kernel/debug/kmemleak [ 34.991354] kvm [304]: nVHE hyp BUG at: [] __kvm_nvhe_handle_host_mem_abort+0x270/0x290! [ 34.991580] kvm [304]: Hyp Offset: 0xfffe8be807e00000 [ 34.991813] Kernel panic - not syncing: HYP panic: [ 34.991813] PS:600003c9 PC:0000f418011a3750 ESR:00000000f2000800 [ 34.991813] FAR:ffff000439200000 HPFAR:0000000004792000 PAR:0000000000000000 [ 34.991813] VCPU:0000000000000000 [ 34.993660] CPU: 0 PID: 304 Comm: bash Not tainted 5.19.0-rc2 #102 [ 34.994059] Hardware name: linux,dummy-virt (DT) [ 34.994452] Call trace: [ 34.994641] dump_backtrace.part.0+0xcc/0xe0 [ 34.994932] show_stack+0x18/0x6c [ 34.995094] dump_stack_lvl+0x68/0x84 [ 34.995276] dump_stack+0x18/0x34 [ 34.995484] panic+0x16c/0x354 [ 34.995673] __hyp_pgtable_total_pages+0x0/0x60 [ 34.995933] scan_block+0x74/0x12c [ 34.996129] scan_gray_list+0xd8/0x19c [ 34.996332] kmemleak_scan+0x2c8/0x580 [ 34.996535] kmemleak_write+0x340/0x4a0 [ 34.996744] full_proxy_write+0x60/0xbc [ 34.996967] vfs_write+0xc4/0x2b0 [ 34.997136] ksys_write+0x68/0xf4 [ 34.997311] __arm64_sys_write+0x20/0x2c [ 34.997532] invoke_syscall+0x48/0x114 [ 34.997779] el0_svc_common.constprop.0+0x44/0xec [ 34.998029] do_el0_svc+0x2c/0xc0 [ 34.998205] el0_svc+0x2c/0x84 [ 34.998421] el0t_64_sync_handler+0xf4/0x100 [ 34.998653] el0t_64_sync+0x18c/0x190 [ 34.999252] SMP: stopping secondary CPUs [ 35.000034] Kernel Offset: disabled [ 35.000261] CPU features: 0x800,00007831,00001086 [ 35.000642] Memory Limit: none [ 35.001329] ---[ end Kernel panic - not syncing: HYP panic: [ 35.001329] PS:600003c9 PC:0000f418011a3750 ESR:00000000f2000800 [ 35.001329] FAR:ffff000439200000 HPFAR:0000000004792000 PAR:0000000000000000 [ 35.001329] VCPU:0000000000000000 ]--- Fix this by explicitly excluding the hypervisor's memory pool from kmemleak like we already do for the hyp BSS. Cc: Mike Rapoport Fixes: a7259df76702 ("memblock: make memblock_find_in_range method private") Signed-off-by: Quentin Perret Acked-by: Catalin Marinas Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20220616161135.3997786-1-qperret@google.com --- arch/arm64/kvm/arm.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index a0188144a122..83a7f61354d3 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -2112,11 +2112,11 @@ static int finalize_hyp_mode(void) return 0; /* - * Exclude HYP BSS from kmemleak so that it doesn't get peeked - * at, which would end badly once the section is inaccessible. - * None of other sections should ever be introspected. + * Exclude HYP sections from kmemleak so that they don't get peeked + * at, which would end badly once inaccessible. */ kmemleak_free_part(__hyp_bss_start, __hyp_bss_end - __hyp_bss_start); + kmemleak_free_part(__va(hyp_mem_base), hyp_mem_size); return pkvm_drop_host_privileges(); } From cbc6d44867a24130ee528c20cffcbc28b3e09693 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 16 Jun 2022 09:53:18 +0100 Subject: [PATCH 2/2] KVM: arm64: Add Oliver as a reviewer Oliver Upton has agreed to help with reviewing the KVM/arm64 patches, and has been doing so for a while now, so adding him as to the reviewer list. Note that Oliver is using a different email address for this purpose, rather than the one his been using for his other contributions. Signed-off-by: Marc Zyngier Acked-by: Oliver Upton Link: https://lore.kernel.org/r/20220616085318.1303657-1-maz@kernel.org --- MAINTAINERS | 1 + 1 file changed, 1 insertion(+) diff --git a/MAINTAINERS b/MAINTAINERS index a6d3bd9d2a8d..7192d1277558 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -10821,6 +10821,7 @@ M: Marc Zyngier R: James Morse R: Alexandru Elisei R: Suzuki K Poulose +R: Oliver Upton L: linux-arm-kernel@lists.infradead.org (moderated for non-subscribers) L: kvmarm@lists.cs.columbia.edu (moderated for non-subscribers) S: Maintained