On 08/01/15 15:22, Jan Beulich wrote:
> - drop clearing of excessive multicall arguments in compat case (no
> longer needed now that hypercall_xlat_continuation() only checks the
> actual arguments)
> - latch current into a local variable
> - use the cached value of hvm_guest_x86_mode() instead of re-executing
> it
> - scope restrict "regs"
> - while at it, convert the remaining two argument checking BUG_ON()s in
> hypercall_xlat_continuation() to ASSERT()s
>
> Signed-off-by: Jan Beulich <jbeul...@suse.com>
Reviewed-by: Andrew Cooper <andrew.coop...@citrix.com>
There appear to other many other places which could benifit from a
caching of guest_x86_mode() (especially in the nested virt case). Is it
worth considering unconditionally calculating on vmexit and removing the
function?
>
> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -1675,7 +1675,6 @@ unsigned long hypercall_create_continuat
> unsigned int op, const char *format, ...)
> {
> struct mc_state *mcs = ¤t->mc_state;
> - struct cpu_user_regs *regs;
> const char *p = format;
> unsigned long arg;
> unsigned int i;
> @@ -1689,26 +1688,23 @@ unsigned long hypercall_create_continuat
>
> for ( i = 0; *p != '\0'; i++ )
> mcs->call.args[i] = next_arg(p, args);
> - if ( is_pv_32on64_domain(current->domain) )
> - {
> - for ( ; i < 6; i++ )
> - mcs->call.args[i] = 0;
> - }
> }
> else
> {
> - regs = guest_cpu_user_regs();
> - regs->eax = op;
> + struct cpu_user_regs *regs = guest_cpu_user_regs();
> + struct vcpu *curr = current;
> +
> + regs->eax = op;
>
> /* Ensure the hypercall trap instruction is re-executed. */
> - if ( is_pv_vcpu(current) )
> + if ( is_pv_vcpu(curr) )
> regs->eip -= 2; /* re-execute 'syscall' / 'int $xx' */
> else
> - current->arch.hvm_vcpu.hcall_preempted = 1;
> + curr->arch.hvm_vcpu.hcall_preempted = 1;
>
> - if ( is_pv_vcpu(current) ?
> - !is_pv_32on64_vcpu(current) :
> - (hvm_guest_x86_mode(current) == 8) )
> + if ( is_pv_vcpu(curr) ?
> + !is_pv_32on64_vcpu(curr) :
> + curr->arch.hvm_vcpu.hcall_64bit )
> {
> for ( i = 0; *p != '\0'; i++ )
> {
> @@ -1759,9 +1755,8 @@ int hypercall_xlat_continuation(unsigned
>
> ASSERT(nr <= ARRAY_SIZE(mcs->call.args));
> ASSERT(!(mask >> nr));
> -
> - BUG_ON(id && *id >= nr);
> - BUG_ON(id && (mask & (1U << *id)));
> + ASSERT(!id || *id < nr);
> + ASSERT(!id || !(mask & (1U << *id)));
>
> va_start(args, mask);
>
>
>
>
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
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