linux-kernel - [PATCH] KVM: arm64: Update comment of create_hyp

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Message-Id: <20221027091523.139598-1-r09922117@csie.ntu.edu.tw>
Date:   Thu, 27 Oct 2022 17:15:23 +0800
From:   Wei-Lin Chang <r09922117@...e.ntu.edu.tw>
To:     maz@...nel.org
Cc:     james.morse@....com, alexandru.elisei@....com,
        suzuki.poulose@....com, oliver.upton@...ux.dev,
        catalin.marinas@....com, will@...nel.org,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
        kvmarm@...ts.cs.columbia.edu, linux-kernel@...r.kernel.org,
        Wei-Lin Chang <r09922117@...e.ntu.edu.tw>
Subject: [PATCH] KVM: arm64: Update comment of create_hyp_mappings

HYP_PAGE_OFFSET is removed since 4.8, and the method for generating Hyp
VAs has evolved. Update the functional description of
create_hyp_mappings accordingly.

Signed-off-by: Wei-Lin Chang <r09922117@...e.ntu.edu.tw>
---
 arch/arm64/kvm/mmu.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index c9a13e487..a9ae4a3f9 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -424,9 +424,10 @@ void kvm_unshare_hyp(void *from, void *to)
  * @to:		The virtual kernel end address of the range (exclusive)
  * @prot:	The protection to be applied to this range
  *
- * The same virtual address as the kernel virtual address is also used
- * in Hyp-mode mapping (modulo HYP_PAGE_OFFSET) to the same underlying
- * physical pages.
+ * The Hyp virtual address is generated by masking the kernel VA with
+ * va_mask then inserting tag_val for the higher bits starting from
+ * tag_lsb. See kvm_compute_layout() in va_layout.c for more info.
+ * Both Hyp VA and kernel VA ranges map to the same underlying physical pages.
  */
 int create_hyp_mappings(void *from, void *to, enum kvm_pgtable_prot prot)
 {
-- 
2.34.1