Shiqing Gao d90dbc0d91 hv: check the capability of XSAVES/XRSTORS instructions before execution ... For platforms that do not support XSAVES/XRSTORS instructions, like QEMU, executing these instructions causes #UD. This patch adds the check before the execution of XSAVES/XRSTORS instructions. It also refines the logic inside rstore_xsave_area for the following reason: If XSAVES/XRSTORS instructions are supported, restore XSAVE area if any of the following conditions is met: 1. "vcpu->launched" is false (state initialization for guest) 2. "vcpu->arch.xsave_enabled" is true (state restoring for guest) * Before vCPU is launched, condition 1 is satisfied. * After vCPU is launched, condition 2 is satisfied because is_valid_xsave_combination() guarantees that "vcpu->arch.xsave_enabled" is consistent with pcpu_has_cap(X86_FEATURE_XSAVES). Therefore, the check against "vcpu->launched" and "vcpu->arch.xsave_enabled" can be eliminated here. Tracked-On: #6481 Signed-off-by: Shiqing Gao <shiqing.gao@intel.com> Acked-by: Eddie Dong <eddie.dong@Intel.com>		2021-08-26 09:42:23 +08:00
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x86	hv: check the capability of XSAVES/XRSTORS instructions before execution	2021-08-26 09:42:23 +08:00