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| author | Andy Lutomirski <luto@kernel.org> | 2020-02-28 10:42:48 -0800 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-05-19 15:53:57 +0200 |
| commit | ef68017eb5704eb2b0577c3aa6619e13caf2b59f (patch) | |
| tree | a2a446d82225fc8adf7badb026cb869573371a39 /arch/x86/mm | |
| parent | af1e56b78534c38bb0e0c712ca70e59f816b74e9 (diff) | |
| download | linux-ef68017eb5704eb2b0577c3aa6619e13caf2b59f.tar.bz2 | |
x86/kvm: Handle async page faults directly through do_page_fault()
KVM overloads #PF to indicate two types of not-actually-page-fault
events. Right now, the KVM guest code intercepts them by modifying
the IDT and hooking the #PF vector. This makes the already fragile
fault code even harder to understand, and it also pollutes call
traces with async_page_fault and do_async_page_fault for normal page
faults.
Clean it up by moving the logic into do_page_fault() using a static
branch. This gets rid of the platform trap_init override mechanism
completely.
[ tglx: Fixed up 32bit, removed error code from the async functions and
massaged coding style ]
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134059.169270470@linutronix.de
Diffstat (limited to 'arch/x86/mm')
| -rw-r--r-- | arch/x86/mm/fault.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index a51df516b87b..6486ccec1b0e 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -30,6 +30,7 @@ #include <asm/desc.h> /* store_idt(), ... */ #include <asm/cpu_entry_area.h> /* exception stack */ #include <asm/pgtable_areas.h> /* VMALLOC_START, ... */ +#include <asm/kvm_para.h> /* kvm_handle_async_pf */ #define CREATE_TRACE_POINTS #include <asm/trace/exceptions.h> @@ -1523,6 +1524,24 @@ do_page_fault(struct pt_regs *regs, unsigned long hw_error_code, unsigned long address) { prefetchw(¤t->mm->mmap_sem); + /* + * KVM has two types of events that are, logically, interrupts, but + * are unfortunately delivered using the #PF vector. These events are + * "you just accessed valid memory, but the host doesn't have it right + * now, so I'll put you to sleep if you continue" and "that memory + * you tried to access earlier is available now." + * + * We are relying on the interrupted context being sane (valid RSP, + * relevant locks not held, etc.), which is fine as long as the + * interrupted context had IF=1. We are also relying on the KVM + * async pf type field and CR2 being read consistently instead of + * getting values from real and async page faults mixed up. + * + * Fingers crossed. + */ + if (kvm_handle_async_pf(regs, (u32)address)) + return; + trace_page_fault_entries(regs, hw_error_code, address); if (unlikely(kmmio_fault(regs, address))) |