[Xen-devel] [PATCH RFC 3/3] Revert "libxc: create an initial FPU state for HVM guests"

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

This reverts commit d64dbbcc7c9934a46126c59d78536235908377ad.

Xen always set the FPU as initialized when loading a HVM context, so libxc
has to provide a valid FPU context when setting the CPU registers.

This is a stop-gap measure in order to unblock OSSTest Windows 7 failures
while a proper fix for the HVM CPU save/restore is being worked on.

Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 tools/libxc/xc_dom_x86.c | 38 --------------------------------------
 1 file changed, 38 deletions(-)

diff --git a/tools/libxc/xc_dom_x86.c b/tools/libxc/xc_dom_x86.c
index 034abe0..dd331bf 100644
--- a/tools/libxc/xc_dom_x86.c
+++ b/tools/libxc/xc_dom_x86.c
@@ -841,27 +841,6 @@ static int vcpu_hvm(struct xc_dom_image *dom)
         struct hvm_save_descriptor end_d;
         HVM_SAVE_TYPE(END) end;
     } bsp_ctx;
-    /*
-     * The layout of the fpu context structure is the same for
-     * both 32 and 64 bits.
-     */
-    struct {
-        uint16_t fcw;
-        uint16_t fsw;
-        uint8_t ftw;
-        uint8_t rsvd1;
-        uint16_t fop;
-        union {
-            uint64_t addr;
-            struct {
-                uint32_t offs;
-                uint16_t sel;
-                uint16_t rsvd;
-            };
-        } fip, fdp;
-        uint32_t mxcsr;
-        uint32_t mxcsr_mask;
-    } *fpu_ctxt;
     uint8_t *full_ctx = NULL;
     int rc;
 
@@ -929,23 +908,6 @@ static int vcpu_hvm(struct xc_dom_image *dom)
     /* Set the control registers. */
     bsp_ctx.cpu.cr0 = X86_CR0_PE | X86_CR0_ET;
 
-    /*
-     * XXX: Set initial FPU state.
-     *
-     * This should be removed once Xen is able to know if the
-     * FPU state saved is valid or not, now Xen always sets
-     * fpu_initialised to true regardless of the FPU state.
-     *
-     * The code below mimics the FPU sate after executing
-     * fninit
-     * ldmxcsr 0x1f80
-     */
-    fpu_ctxt = (typeof(fpu_ctxt))bsp_ctx.cpu.fpu_regs;
-
-    fpu_ctxt->fcw = 0x37f;
-    fpu_ctxt->ftw = 0xff;
-    fpu_ctxt->mxcsr = 0x1f80;
-
     /* Set the IP. */
     bsp_ctx.cpu.rip = dom->parms.phys_entry;
 
-- 
1.9.5 (Apple Git-50.3)


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