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| author | Ackerley Tng <ackerleytng@google.com> | 2023-02-27 21:06:01 +0300 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2023-03-25 00:20:51 +0300 |
| commit | 8264e85560e5fae942ca42aae1df7daeb5aaa30e (patch) | |
| tree | 03b99049128505300470fb79a54dec95c137f51e /tools/testing/selftests/kvm/lib/x86_64/processor.c | |
| parent | 5b1abc285a083f76e9987efa9e78ecc18d5d202f (diff) | |
| download | linux-8264e85560e5fae942ca42aae1df7daeb5aaa30e.tar.xz | |
KVM: selftests: Adjust VM's initial stack address to align with SysV ABI spec
Align the guest stack to match calling sequence requirements in
section "The Stack Frame" of the System V ABI AMD64 Architecture
Processor Supplement, which requires the value (%rsp + 8), NOT %rsp,
to be a multiple of 16 when control is transferred to the function
entry point. I.e. in a normal function call, %rsp needs to be 16-byte
aligned _before_ CALL, not after.
This fixes unexpected #GPs in guest code when the compiler uses SSE
instructions, e.g. to initialize memory, as many SSE instructions
require memory operands (including those on the stack) to be
16-byte-aligned.
Signed-off-by: Ackerley Tng <ackerleytng@google.com>
Link: https://lore.kernel.org/r/20230227180601.104318-1-ackerleytng@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'tools/testing/selftests/kvm/lib/x86_64/processor.c')
| -rw-r--r-- | tools/testing/selftests/kvm/lib/x86_64/processor.c | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c index c39a4353ba19..c09cd151fbe0 100644 --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c @@ -5,6 +5,7 @@ * Copyright (C) 2018, Google LLC. */ +#include "linux/bitmap.h" #include "test_util.h" #include "kvm_util.h" #include "processor.h" @@ -573,6 +574,21 @@ struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id, DEFAULT_GUEST_STACK_VADDR_MIN, MEM_REGION_DATA); + stack_vaddr += DEFAULT_STACK_PGS * getpagesize(); + + /* + * Align stack to match calling sequence requirements in section "The + * Stack Frame" of the System V ABI AMD64 Architecture Processor + * Supplement, which requires the value (%rsp + 8) to be a multiple of + * 16 when control is transferred to the function entry point. + * + * If this code is ever used to launch a vCPU with 32-bit entry point it + * may need to subtract 4 bytes instead of 8 bytes. + */ + TEST_ASSERT(IS_ALIGNED(stack_vaddr, PAGE_SIZE), + "__vm_vaddr_alloc() did not provide a page-aligned address"); + stack_vaddr -= 8; + vcpu = __vm_vcpu_add(vm, vcpu_id); vcpu_init_cpuid(vcpu, kvm_get_supported_cpuid()); vcpu_setup(vm, vcpu); @@ -580,7 +596,7 @@ struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id, /* Setup guest general purpose registers */ vcpu_regs_get(vcpu, ®s); regs.rflags = regs.rflags | 0x2; - regs.rsp = stack_vaddr + (DEFAULT_STACK_PGS * getpagesize()); + regs.rsp = stack_vaddr; regs.rip = (unsigned long) guest_code; vcpu_regs_set(vcpu, ®s); |