From: "jemmy858585" <jemmy858585@gmail.com>
To: "kvm" <kvm@vger.kernel.org>
Subject: some question in function do_vmx_vcpu_run, if anyone knows , please tell me,thanks.
Date: Sun, 31 Oct 2010 16:50:23 +0800 [thread overview]
Message-ID: <201010311650185006548@gmail.com> (raw)
in the function do_vmx_vcpu_run , there are some code which i didn't understand.
question one:
".Lkvm_vmx_return: "
/* Save guest registers, load host registers, keep flags */
"xchg %0, (%%"R"sp) \n\t"
"mov %%"R"ax, %c[rax](%0) \n\t"
"mov %%"R"bx, %c[rbx](%0) \n\t"
"push"Q" (%%"R"sp); pop"Q" %c[rcx](%0) \n\t"
"mov %%"R"dx, %c[rdx](%0) \n\t"
"mov %%"R"si, %c[rsi](%0) \n\t"
"mov %%"R"di, %c[rdi](%0) \n\t"
"mov %%"R"bp, %c[rbp](%0) \n\t"
why need
"xchg %0, (%%"R"sp) \n\t"
and
"push"Q" (%%"R"sp); pop"Q" %c[rcx](%0) \n\t"
I think rsp will restore when vm exits, why we change it?
question two:
before vm entry
/* Store host registers */
"push %%"R"dx; push %%"R"bp;"
"push %%"R"cx \n\t"
and after vm exit
"pop %%"R"bp; pop %%"R"bp; pop %%"R"dx \n\t"
why we need push rdx,rbp,rcx, and didn't pop rcx; and why we didn't save other register?
--------------
jemmy858585
2010-10-31
reply other threads:[~2010-10-31 8:48 UTC|newest]
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