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Commit 196d0419 authored by Mark Rutland's avatar Mark Rutland Committed by Greg Kroah-Hartman
Browse files

arm64: KVM: Add SMCCC_ARCH_WORKAROUND_1 fast handling 




From: Marc Zyngier <marc.zyngier@arm.com>

commit f72af90c3783d924337624659b43e2d36f1b36b4 upstream.

We want SMCCC_ARCH_WORKAROUND_1 to be fast. As fast as possible.
So let's intercept it as early as we can by testing for the
function call number as soon as we've identified a HVC call
coming from the guest.

Tested-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com> [v4.9 backport]
Tested-by: default avatarGreg Hackmann <ghackmann@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c9ae3d57

arch/arm64/kvm/hyp/hyp-entry.S

+18 −2
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */



#include <linux/arm-smccc.h>

#include <linux/linkage.h>



#include <asm/alternative.h>
@@ -79,10 +80,11 @@ alternative_endif 
	lsr	x0, x1, #ESR_ELx_EC_SHIFT



	cmp	x0, #ESR_ELx_EC_HVC64

	ccmp	x0, #ESR_ELx_EC_HVC32, #4, ne

	b.ne	el1_trap



	mrs	x1, vttbr_el2		// If vttbr is valid, the 64bit guest

	cbnz	x1, el1_trap		// called HVC

	mrs	x1, vttbr_el2		// If vttbr is valid, the guest

	cbnz	x1, el1_hvc_guest	// called HVC



	/* Here, we're pretty sure the host called HVC. */

	ldp	x0, x1, [sp], #16
@@ -101,6 +103,20 @@ alternative_endif 


2:	eret



el1_hvc_guest:

	/*

	 * Fastest possible path for ARM_SMCCC_ARCH_WORKAROUND_1.

	 * The workaround has already been applied on the host,

	 * so let's quickly get back to the guest. We don't bother

	 * restoring x1, as it can be clobbered anyway.

	 */

	ldr	x1, [sp]				// Guest's x0

	eor	w1, w1, #ARM_SMCCC_ARCH_WORKAROUND_1

	cbnz	w1, el1_trap

	mov	x0, x1

	add	sp, sp, #16

	eret



el1_trap:

	/*

	 * x0: ESR_EC