Commit b0de5680 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
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KVM: x86/mmu: Use MMIO SPTE bits 53 and 52 for the MMIO generation 



Use bits 53 and 52 for the MMIO generation now that they're not used to
identify MMIO SPTEs.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20210225204749.1512652-14-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 8a406c89

arch/x86/kvm/mmu/spte.c

+0 −1
Original line number Diff line number Diff line
@@ -42,7 +42,6 @@ static u64 generation_mmio_spte_mask(u64 gen) 
	u64 mask;



	WARN_ON(gen & ~MMIO_SPTE_GEN_MASK);

	BUILD_BUG_ON((MMIO_SPTE_GEN_HIGH_MASK | MMIO_SPTE_GEN_LOW_MASK) & SPTE_TDP_AD_MASK);



	mask = (gen << MMIO_SPTE_GEN_LOW_SHIFT) & MMIO_SPTE_GEN_LOW_MASK;

	mask |= (gen << MMIO_SPTE_GEN_HIGH_SHIFT) & MMIO_SPTE_GEN_HIGH_MASK;

arch/x86/kvm/mmu/spte.h

+4 −4
Original line number Diff line number Diff line
@@ -65,11 +65,11 @@ static_assert(SPTE_TDP_AD_ENABLED_MASK == 0); 
#define SPTE_MMU_WRITEABLE	(1ULL << (PT_FIRST_AVAIL_BITS_SHIFT + 1))



/*

 * Due to limited space in PTEs, the MMIO generation is a 18 bit subset of

 * Due to limited space in PTEs, the MMIO generation is a 20 bit subset of

 * the memslots generation and is derived as follows:

 *

 * Bits 0-8 of the MMIO generation are propagated to spte bits 3-11

 * Bits 9-17 of the MMIO generation are propagated to spte bits 54-62

 * Bits 9-19 of the MMIO generation are propagated to spte bits 52-62

 *

 * The KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS flag is intentionally not included in

 * the MMIO generation number, as doing so would require stealing a bit from
@@ -82,7 +82,7 @@ static_assert(SPTE_TDP_AD_ENABLED_MASK == 0); 
#define MMIO_SPTE_GEN_LOW_START		3

#define MMIO_SPTE_GEN_LOW_END		11



#define MMIO_SPTE_GEN_HIGH_START	PT64_SECOND_AVAIL_BITS_SHIFT

#define MMIO_SPTE_GEN_HIGH_START	52

#define MMIO_SPTE_GEN_HIGH_END		62



#define MMIO_SPTE_GEN_LOW_MASK		GENMASK_ULL(MMIO_SPTE_GEN_LOW_END, \
@@ -94,7 +94,7 @@ static_assert(SPTE_TDP_AD_ENABLED_MASK == 0); 
#define MMIO_SPTE_GEN_HIGH_BITS		(MMIO_SPTE_GEN_HIGH_END - MMIO_SPTE_GEN_HIGH_START + 1)



/* remember to adjust the comment above as well if you change these */

static_assert(MMIO_SPTE_GEN_LOW_BITS == 9 && MMIO_SPTE_GEN_HIGH_BITS == 9);

static_assert(MMIO_SPTE_GEN_LOW_BITS == 9 && MMIO_SPTE_GEN_HIGH_BITS == 11);



#define MMIO_SPTE_GEN_LOW_SHIFT		(MMIO_SPTE_GEN_LOW_START - 0)

#define MMIO_SPTE_GEN_HIGH_SHIFT	(MMIO_SPTE_GEN_HIGH_START - MMIO_SPTE_GEN_LOW_BITS)