Re: [PATCH v6 6/7] KVM: x86: Untag address when LAM applicable

[Binbin Wu <binbin.wu@linux.intel.com>]

On 3/19/2023 4:49 PM, Binbin Wu wrote:
> Untag address for 64-bit memory/mmio operand in instruction emulations
> and vmexit handlers when LAM is applicable.
>
> For instruction emulation, untag address in __linearize() before
> canonical check. LAM doesn't apply to instruction fetch and invlpg,
> use KVM_X86_UNTAG_ADDR_SKIP_LAM to skip LAM untag.
>
> For vmexit handlings related to 64-bit linear address:
> - Cases need to untag address
>    Operand(s) of VMX instructions and INVPCID
>    Operand(s) of SGX ENCLS
>    Linear address in INVVPID descriptor.
> - Cases LAM doesn't apply to (no change needed)
>    Operand of INVLPG
>    Linear address in INVPCID descriptor
>
> Co-developed-by: Robert Hoo <robert.hu@linux.intel.com>
> Signed-off-by: Robert Hoo <robert.hu@linux.intel.com>
> Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
> ---
>   arch/x86/kvm/emulate.c    | 25 +++++++++++++++++--------
>   arch/x86/kvm/vmx/nested.c |  2 ++
>   arch/x86/kvm/vmx/sgx.c    |  1 +
>   arch/x86/kvm/x86.c        |  4 ++++
>   4 files changed, 24 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index a630c5db971c..c46f0162498e 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -688,7 +688,8 @@ static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
>   				       struct segmented_address addr,
>   				       unsigned *max_size, unsigned size,
>   				       bool write, bool fetch,
> -				       enum x86emul_mode mode, ulong *linear)
> +				       enum x86emul_mode mode, ulong *linear,
> +				       u64 untag_flags)
>   {
>   	struct desc_struct desc;
>   	bool usable;
> @@ -701,9 +702,10 @@ static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
>   	*max_size = 0;
>   	switch (mode) {
>   	case X86EMUL_MODE_PROT64:
> -		*linear = la;
> +		*linear = static_call(kvm_x86_untag_addr)(ctxt->vcpu, la, untag_flags);
> +
>   		va_bits = ctxt_virt_addr_bits(ctxt);
> -		if (!__is_canonical_address(la, va_bits))
> +		if (!__is_canonical_address(*linear, va_bits))
>   			goto bad;

Find  la as a local variable, will be used later.
This part will be updated as following to make la untagged to avoid 
further changes:

@@ -701,6 +702,7 @@ static __always_inline int __linearize(struct 
x86_emulate_ctxt *ctxt,
         *max_size = 0;
         switch (mode) {
         case X86EMUL_MODE_PROT64:
+               la = ctxt->ops->untag_addr(ctxt, la, untag_flags);
                 *linear = la;
                 va_bits = ctxt_virt_addr_bits(ctxt);
                 if (!__is_canonical_address(la, va_bits))