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| author | Michael Brown | 2021-02-18 15:30:27 +0100 |
|---|---|---|
| committer | Michael Brown | 2021-02-18 16:38:56 +0100 |
| commit | 900f1f98d3dbb64803e427318ad61c9d7aa6f9bb (patch) | |
| tree | 93397baefd0b1391e321dcdfe04afabd1578e89b /src/arch/x86/transitions/librm.S | |
| parent | [librm] Add missing __asmcall on init_idt() (diff) | |
| download | ipxe-900f1f98d3dbb64803e427318ad61c9d7aa6f9bb.tar.gz ipxe-900f1f98d3dbb64803e427318ad61c9d7aa6f9bb.tar.xz ipxe-900f1f98d3dbb64803e427318ad61c9d7aa6f9bb.zip | |
[librm] Test for FXSAVE/FXRSTOR instruction support
Assume that preservation of the %xmm registers is unnecessary during
installation of iPXE into memory, since this is an operation that by
its nature substantially disrupts large portions of the system anyway
(such as the E820 memory map). This assumption allows us to utilise
the existing CPUID code to check that FXSAVE/FXRSTOR are supported.
Test for support during the call to init_librm and store the flag for
use during subsequent calls to virt_call.
Reduce the scope of TIVOLI_VMM_WORKAROUND to affecting only the call
to check_fxsr(), to reduce #ifdef pollution in the remaining code.
Debugged-by: Johannes Heimansberg <git@jhe.dedyn.io>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Diffstat (limited to 'src/arch/x86/transitions/librm.S')
| -rw-r--r-- | src/arch/x86/transitions/librm.S | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/src/arch/x86/transitions/librm.S b/src/arch/x86/transitions/librm.S index f2fa8c50..5dacb9b0 100644 --- a/src/arch/x86/transitions/librm.S +++ b/src/arch/x86/transitions/librm.S @@ -210,9 +210,7 @@ VC_TMP_CR3: .space 4 VC_TMP_CR4: .space 4 VC_TMP_EMER: .space 8 .endif -#ifdef TIVOLI_VMM_WORKAROUND VC_TMP_FXSAVE: .space 512 -#endif VC_TMP_END: .previous @@ -350,6 +348,13 @@ init_librm_rmode: /* Initialise IDT */ virtcall init_idt +#ifdef TIVOLI_VMM_WORKAROUND + /* Check for FXSAVE/FXRSTOR */ + clc + virtcall check_fxsr + setnc fxsr_supported +#endif + /* Restore registers */ popl %edi popl %ebx @@ -366,6 +371,10 @@ set_seg_base: roll $16, %eax ret + .section ".data16.fxsr_supported", "awx", @progbits +fxsr_supported: /* FXSAVE/FXRSTOR instructions supported */ + .byte 0 + /**************************************************************************** * real_to_prot (real-mode near call, 32-bit virtual return address) * @@ -1007,10 +1016,11 @@ virt_call: cli movw %cs:rm_ds, %ds -#ifdef TIVOLI_VMM_WORKAROUND /* Preserve FPU, MMX and SSE state in temporary static buffer */ + testb $0xff, fxsr_supported + jz 1f fxsave ( rm_tmpbuf + VC_TMP_FXSAVE ) -#endif +1: /* Preserve GDT and IDT in temporary static buffer */ sidt ( rm_tmpbuf + VC_TMP_IDT ) sgdt ( rm_tmpbuf + VC_TMP_GDT ) @@ -1077,10 +1087,11 @@ vc_rmode: wrmsr .endif -#ifdef TIVOLI_VMM_WORKAROUND /* Restore FPU, MMX and SSE state from temporary static buffer */ + testb $0xff, fxsr_supported + jz 1f fxrstor ( rm_tmpbuf + VC_TMP_FXSAVE ) -#endif +1: /* Restore registers and flags and return */ popl %eax /* skip %cs and %ss */ popw %ds |