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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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c1118b3602
On x86_64, kernel text mappings are mapped read-only with CONFIG_DEBUG_RODATA. In that case, KVM will fail to patch VMCALL instructions to VMMCALL as required on AMD processors. The failure mode is currently a divide-by-zero exception, which obviously is a KVM bug that has to be fixed. However, picking the right instruction between VMCALL and VMMCALL will be faster and will help if you cannot upgrade the hypervisor. Reported-by: Chris Webb <chris@arachsys.com> Tested-by: Chris Webb <chris@arachsys.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Acked-by: Borislav Petkov <bp@suse.de> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
138 lines
3.2 KiB
C
138 lines
3.2 KiB
C
#ifndef _ASM_X86_KVM_PARA_H
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#define _ASM_X86_KVM_PARA_H
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#include <asm/processor.h>
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#include <asm/alternative.h>
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#include <uapi/asm/kvm_para.h>
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extern void kvmclock_init(void);
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extern int kvm_register_clock(char *txt);
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#ifdef CONFIG_KVM_GUEST
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bool kvm_check_and_clear_guest_paused(void);
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#else
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static inline bool kvm_check_and_clear_guest_paused(void)
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{
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return false;
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}
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#endif /* CONFIG_KVM_GUEST */
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#ifdef CONFIG_DEBUG_RODATA
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#define KVM_HYPERCALL \
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ALTERNATIVE(".byte 0x0f,0x01,0xc1", ".byte 0x0f,0x01,0xd9", X86_FEATURE_VMMCALL)
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#else
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/* On AMD processors, vmcall will generate a trap that we will
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* then rewrite to the appropriate instruction.
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*/
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#define KVM_HYPERCALL ".byte 0x0f,0x01,0xc1"
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#endif
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/* For KVM hypercalls, a three-byte sequence of either the vmcall or the vmmcall
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* instruction. The hypervisor may replace it with something else but only the
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* instructions are guaranteed to be supported.
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*
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* Up to four arguments may be passed in rbx, rcx, rdx, and rsi respectively.
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* The hypercall number should be placed in rax and the return value will be
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* placed in rax. No other registers will be clobbered unless explicitly
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* noted by the particular hypercall.
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*/
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static inline long kvm_hypercall0(unsigned int nr)
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{
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long ret;
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asm volatile(KVM_HYPERCALL
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: "=a"(ret)
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: "a"(nr)
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: "memory");
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return ret;
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}
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static inline long kvm_hypercall1(unsigned int nr, unsigned long p1)
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{
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long ret;
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asm volatile(KVM_HYPERCALL
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: "=a"(ret)
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: "a"(nr), "b"(p1)
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: "memory");
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return ret;
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}
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static inline long kvm_hypercall2(unsigned int nr, unsigned long p1,
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unsigned long p2)
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{
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long ret;
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asm volatile(KVM_HYPERCALL
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: "=a"(ret)
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: "a"(nr), "b"(p1), "c"(p2)
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: "memory");
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return ret;
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}
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static inline long kvm_hypercall3(unsigned int nr, unsigned long p1,
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unsigned long p2, unsigned long p3)
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{
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long ret;
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asm volatile(KVM_HYPERCALL
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: "=a"(ret)
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: "a"(nr), "b"(p1), "c"(p2), "d"(p3)
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: "memory");
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return ret;
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}
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static inline long kvm_hypercall4(unsigned int nr, unsigned long p1,
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unsigned long p2, unsigned long p3,
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unsigned long p4)
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{
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long ret;
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asm volatile(KVM_HYPERCALL
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: "=a"(ret)
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: "a"(nr), "b"(p1), "c"(p2), "d"(p3), "S"(p4)
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: "memory");
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return ret;
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}
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#ifdef CONFIG_KVM_GUEST
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bool kvm_para_available(void);
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unsigned int kvm_arch_para_features(void);
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void __init kvm_guest_init(void);
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void kvm_async_pf_task_wait(u32 token);
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void kvm_async_pf_task_wake(u32 token);
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u32 kvm_read_and_reset_pf_reason(void);
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extern void kvm_disable_steal_time(void);
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#ifdef CONFIG_PARAVIRT_SPINLOCKS
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void __init kvm_spinlock_init(void);
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#else /* !CONFIG_PARAVIRT_SPINLOCKS */
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static inline void kvm_spinlock_init(void)
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{
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}
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#endif /* CONFIG_PARAVIRT_SPINLOCKS */
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#else /* CONFIG_KVM_GUEST */
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#define kvm_guest_init() do {} while (0)
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#define kvm_async_pf_task_wait(T) do {} while(0)
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#define kvm_async_pf_task_wake(T) do {} while(0)
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static inline bool kvm_para_available(void)
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{
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return 0;
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}
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static inline unsigned int kvm_arch_para_features(void)
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{
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return 0;
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}
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static inline u32 kvm_read_and_reset_pf_reason(void)
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{
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return 0;
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}
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static inline void kvm_disable_steal_time(void)
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{
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return;
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}
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#endif
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#endif /* _ASM_X86_KVM_PARA_H */
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