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/* SPDX-License-Identifier: GPL-2.0-or-later */
/******************************************************************************
* arch/x86/pv/hypercall.c
*
* PV hypercall dispatching routines
*
* Copyright (c) 2017 Citrix Systems Ltd.
*/
#include <xen/compiler.h>
#include <xen/hypercall.h>
#include <xen/nospec.h>
#include <xen/trace.h>
#include <asm/apic.h>
#include <asm/multicall.h>
#include <irq_vectors.h>
/* Forced inline to cause 'compat' to be evaluated at compile time. */
static void always_inline
_pv_hypercall(struct cpu_user_regs *regs, bool compat)
{
struct vcpu *curr = current;
unsigned long eax;
ASSERT(guest_kernel_mode(curr, regs));
curr->hcall_preempted = false;
if ( !compat )
{
unsigned long rdi = regs->rdi;
unsigned long rsi = regs->rsi;
unsigned long rdx = regs->rdx;
unsigned long r10 = regs->r10;
unsigned long r8 = regs->r8;
eax = regs->rax;
if ( unlikely(tb_init_done) )
{
unsigned long args[5] = { rdi, rsi, rdx, r10, r8 };
__trace_hypercall(TRC_PV_HYPERCALL_V2, eax, args);
}
call_handlers_pv64(eax, regs->rax, rdi, rsi, rdx, r10, r8);
if ( !curr->hcall_preempted && regs->rax != -ENOSYS )
clobber_regs(regs, eax, pv, 64);
}
#ifdef CONFIG_PV32
else
{
unsigned int ebx = regs->ebx;
unsigned int ecx = regs->ecx;
unsigned int edx = regs->edx;
unsigned int esi = regs->esi;
unsigned int edi = regs->edi;
eax = regs->eax;
if ( unlikely(tb_init_done) )
{
unsigned long args[5] = { ebx, ecx, edx, esi, edi };
__trace_hypercall(TRC_PV_HYPERCALL_V2, eax, args);
}
curr->hcall_compat = true;
call_handlers_pv32(eax, regs->eax, ebx, ecx, edx, esi, edi);
curr->hcall_compat = false;
if ( !curr->hcall_preempted && regs->eax != -ENOSYS )
clobber_regs(regs, eax, pv, 32);
}
#endif /* CONFIG_PV32 */
/*
* PV guests use SYSCALL or INT $0x82 to make a hypercall, both of which
* have trap semantics. If the hypercall has been preempted, rewind the
* instruction pointer to reexecute the instruction.
*/
if ( curr->hcall_preempted )
regs->rip -= 2;
perfc_incra(hypercalls, eax);
}
enum mc_disposition pv_do_multicall_call(struct mc_state *state)
{
struct vcpu *curr = current;
unsigned long op;
#ifdef CONFIG_PV32
if ( is_pv_32bit_vcpu(curr) )
{
struct compat_multicall_entry *call = &state->compat_call;
op = call->op;
call_handlers_pv32(op, call->result, call->args[0], call->args[1],
call->args[2], call->args[3], call->args[4]);
}
else
#endif
{
struct multicall_entry *call = &state->call;
op = call->op;
call_handlers_pv64(op, call->result, call->args[0], call->args[1],
call->args[2], call->args[3], call->args[4]);
}
return unlikely(op == __HYPERVISOR_iret)
? mc_exit
: likely(guest_kernel_mode(curr, guest_cpu_user_regs()))
? mc_continue : mc_preempt;
}
void pv_ring3_init_hypercall_page(void *p)
{
unsigned int i;
for ( i = 0; i < (PAGE_SIZE / 32); i++, p += 32 )
{
if ( unlikely(i == __HYPERVISOR_iret) )
{
/*
* HYPERVISOR_iret is special because it doesn't return and
* expects a special stack frame. Guests jump at this transfer
* point instead of calling it.
*/
*(u8 *)(p+ 0) = 0x51; /* push %rcx */
*(u16 *)(p+ 1) = 0x5341; /* push %r11 */
*(u8 *)(p+ 3) = 0x50; /* push %rax */
*(u8 *)(p+ 4) = 0xb8; /* mov $__HYPERVISOR_iret, %eax */
*(u32 *)(p+ 5) = __HYPERVISOR_iret;
*(u16 *)(p+ 9) = 0x050f; /* syscall */
continue;
}
*(u8 *)(p+ 0) = 0x51; /* push %rcx */
*(u16 *)(p+ 1) = 0x5341; /* push %r11 */
*(u8 *)(p+ 3) = 0xb8; /* mov $<i>,%eax */
*(u32 *)(p+ 4) = i;
*(u16 *)(p+ 8) = 0x050f; /* syscall */
*(u16 *)(p+10) = 0x5b41; /* pop %r11 */
*(u8 *)(p+12) = 0x59; /* pop %rcx */
*(u8 *)(p+13) = 0xc3; /* ret */
}
}
#ifdef CONFIG_PV32
void pv_ring1_init_hypercall_page(void *p)
{
unsigned int i;
for ( i = 0; i < (PAGE_SIZE / 32); i++, p += 32 )
{
if ( unlikely(i == __HYPERVISOR_iret) )
{
/*
* HYPERVISOR_iret is special because it doesn't return and
* expects a special stack frame. Guests jump at this transfer
* point instead of calling it.
*/
*(u8 *)(p+ 0) = 0x50; /* push %eax */
*(u8 *)(p+ 1) = 0xb8; /* mov $__HYPERVISOR_iret, %eax */
*(u32 *)(p+ 2) = __HYPERVISOR_iret;
*(u16 *)(p+ 6) = (HYPERCALL_VECTOR << 8) | 0xcd; /* int $xx */
continue;
}
*(u8 *)(p+ 0) = 0xb8; /* mov $<i>,%eax */
*(u32 *)(p+ 1) = i;
*(u16 *)(p+ 5) = (HYPERCALL_VECTOR << 8) | 0xcd; /* int $xx */
*(u8 *)(p+ 7) = 0xc3; /* ret */
}
}
void do_entry_int82(struct cpu_user_regs *regs)
{
if ( unlikely(untrusted_msi) )
check_for_unexpected_msi((uint8_t)regs->entry_vector);
_pv_hypercall(regs, true /* compat */);
}
#endif
void pv_hypercall(struct cpu_user_regs *regs)
{
_pv_hypercall(regs, false /* native */);
}
/*
* Local variables:
* mode: C
* c-file-style: "BSD"
* c-basic-offset: 4
* tab-width: 4
* indent-tabs-mode: nil
* End:
*/
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