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KVM: selftests: Add support for #DE exception fixup

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Add support for handling #DE (divide error) exceptions in KVM selftests
so that the fastops test can verify KVM correctly handles #DE when
emulating DIV or IDIV on behalf of the guest.  Morph #DE to 0xff (i.e.
to -1) as a mostly-arbitrary vector to indicate #DE, so that '0' (the
real #DE vector) can still be used to indicate "no exception".

Link: https://lore.kernel.org/r/20250909202835.333554-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2025-09-09 13:28:32 -07:00
parent 665071186c
commit 7b39b6c769
2 changed files with 7 additions and 1 deletions
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6
tools/testing/selftests/kvm/include/x86/processor.h
View File

@ -1179,6 +1179,12 @@ struct idt_entry {
void vm_install_exception_handler(struct kvm_vm *vm, int vector,
void (*handler)(struct ex_regs *));
/*
* Exception fixup morphs #DE to an arbitrary magic vector so that '0' can be
* used to signal "no expcetion".
*/
#define KVM_MAGIC_DE_VECTOR 0xff
/* If a toddler were to say "abracadabra". */
#define KVM_EXCEPTION_MAGIC 0xabacadabaULL

2
tools/testing/selftests/kvm/lib/x86/processor.c
View File

@ -557,7 +557,7 @@ static bool kvm_fixup_exception(struct ex_regs *regs)
return false;
if (regs->vector == DE_VECTOR)
return false;
regs->vector = KVM_MAGIC_DE_VECTOR;
regs->rip = regs->r11;
regs->r9 = regs->vector;